These are the vehicle classing and preparation rules for the Tuner Category of SCCA National Time Trials Competition. The intent of Tuner Category is that these are absolutely streetable, and may even be daily-driven cars. We do not guarantee the competitiveness of every car, as it would be nearly impossible and certainly overly complicated. Once you find your car, make sure if it fits in Tuner Category by scrolling down to see what modifications you're allowed to do.

Tuner Category Classing

The intent of Tuner Category classing is that the category is made up of cars that could be daily-driven, or have been a recent daily driver turned track car. Like any other category, we do not guarantee the competitiveness of every car because of the complication that would involve.

As with Sport Category, we have tried to base the "cars to have" for each class on the most popular cars participating in Track Events and regional autocross events, but this time we focused on cars that are 8–20 years old. These are the cars that might have found a comfortable motorsports niche, or have proven track-worthy well into their life cycle. As we did with Sport Category, there will be a "Balance of Popularity."

If you do not see your car listed, it has not been classed. If you would like to have your car evaluated for classing, use the CONTACT page to fill out a classing request form.

New car makes, types, and models will be classified by the Time Trials Board (TTB) as soon as sufficient information is available to do so. The TTB may reclassify a car at any time up to and including December of the calendar year following that of the initial classification, without the approval of the Board of Directors. “Initial classification” includes the addition of a new listing on an exclusion list.

Tuner Category Classing

Even more awesome cars we considered, and ultimately decided, "This is certainly a dream car, and Max Category is the place for dream cars, whether it's the car you dream to build, or the car you dream to buy."

  M3 GTS 2010
Corvette Z06, ZR1 2015+
Corvette ZR1, 2006-2014
Viper GTS-R or ACR
Hellcat Redeye Widebody 2019
GT500 2020+
720 S
911 Turbo, Turbo S 2013-2015

This is where we're going to put cars that might not quite meet the rules, but we think they can go in this category anyway.

1. Cars listed as eligible in and prepared to the SCCA Road Race National Touring 2, 3 and 4 Rules are permitted to compete in their respective Time Trials Tuner Class provided they run on Time Trials legal tires. Vehicles with this allowance are not permitted to interchange preparation rules otherwise.

2. Cars listed as eligible in and prepared to the SCCA Road Race National Spec Miata Rules are permitted to compete in Time Trials Tuner Class 5 (T5) provided they run on Time Trials legal tires. Vehicles with this allowance are not permitted to interchange preparation rules otherwise.

Note: SCCA Solo Street Prepared has been rejected for Tuner Category inclusion because a full-tilt Street Prepared car is an engine-swapped, intake-manifold customized Frankenstein creation which is awesome, but doesn't belong in Tuner Category.

  Giulia Quadrifoglio 2015+
  R8 V10 2013-15
M3/M4 CS 2018+
M4 GTS 2016+
M6 2012-2018
ATS-V 2016-2019
CTS-V 2009-2015
Corvette Z06 2006-2014
Corvette (Naturally aspirated) 2014+
Camaro ZL1 (all)
Viper 2003-07
550 Maranello 1996-2001
Mustang GT500
GT-R, GT-R Nismo 2008+
GT3 1999-2005
Cayman Base, S 2017+
Cayman GT4 2016-2019
Cayman GT4 4.0 2020+

  NSX 1990-2005
  R8 4.2 V8 2006-15
  RS3 2015+
  TT RS 2012+
  S4 2017+
  M3/M4 2007+
  335i 2006-2013
  M235i 2014-2016
  135i 2008-2013
  M2 Competition 2018+
  M2 2016+
  1M 2011-2012
  M2 2016+
  M6 2005-2010
  CTS-V 2009-2015
Corvette Z06 2001-2005
Corvette 1984 - 2013 Not Otherwise Classed or Excluded
Camaro SS, SS 1LE 2010+
Camaro Z/28 2014-2015
Crossfire SRT6
Viper 1991-02
Scat Pack 2014+
Stealth R/T Turbo
Mustang GT, GT Performance PKG, GT350 2015+
Mustang Boss 302 2012-2013
Q50 Red Sport 400 2016+
XKR 2007-2014
F Type 400
Stinger GT 2018+
IS-F 2007+
GS-F 2016+
  Elise 2005-2008
Exige S 2006-2008
GranTurismo Sport 2012-2019
GranTurismo MC Sportline 2009-2019
  911 Turbo 1997-04
  911 S/4S 2012-2014
911 (SCCA T2)
Boxster/Cayman S 2014-2016
Cayman R 2011-12
Cayman GTS 2014+
Model 3 Performance 2018+
Supra GR 2020+

Integra Type R
TT S 2006-2014
TT (base) 2014+
S3 2013+
S5 2008-2016
E30/E36/E46 M3
M5 1988-2003
Z3 M Roadster/Coupe 1996-2002
Z4 Roadster/Coupe 2002-08
335D 2006-2013
228i 2013+
650i 2005-2010
CTS-V 2004-2007
  SS 2014-2017
Camaro V6 2016+
Camaro 4T
Camaro IROC Z 1988-1992
Cobalt SS (FI) 2005-10
Crossfire 2004-2008
Neon SRT-4
Charger R/T 2001+
124 Abarth
Focus RS 2015+
Mustang (V8) 1979-2014
Mustang EcoBoost 2015+
Mustang V6 2011+
Civic Type R
Genesis R Spec (2.0T & 3.8)
Veloster N 2019+
G35 2002-2007
G37 2007-2015
Q50 3.0t Sport 2016+
  RC200T F Sport 2015+
GS300 V8 1997-2005
RX-7 1992-1995
MazdaSpeed6 All
SLK 250 2011-2019
CLK55 AMG 2000-2003
Cooper S JCW All
Evo 2003+
Z-Cars (Naturally Aspirated)
GTO 2004-2006
Solstice GXP 2007-09
Firebird Firehawk - 1993-1997
Cayman S/Boxster Base & S 2005-2012
Cayman (base) 2014-2016
Boxster S 1996-2004
911 Carrera 2, 4, S and 4S 1999-2008
944 Turbo
Macan S 2014+
Sky Redline 2007-10
WRX (All, including STI)
Legacy GT 2003-2009
MR2 Turbo (1989-1995)
Camry LE 2017+
Golf R
S60 R 2004-2007

RSX (All)
Integra (All)
TSX 2004-14
TT 1.8T 1998-2006
TT VR6 2003-2010
A4 1.8T 2001-2006
A4 2.0T 2004-2009
E36/E46 All, Non-M
540i 1992-1996
528i 1995-2001
328i 2004-2013
325i 2006-2013
128i 2008-2013
Z3 2.5 2000-2002
CTS V6 2004-2007
Bolt 2017+
Volt 2016+
Cobalt (NA) 2005-10
Cruz LT 2014+
Conquest TSI 1987-1989
Dart SXT 1.4T 2013-2016
500 Arbarth 2008+
Fiesta ST (All)
Focus ST (All)
Focus ZX3 2004-2011
Mustang V6 1999-2010
Crown Vic 1997-2007
Taurus SHO 1989-99
S2000 (All)
Civic Si 1995+
Hyundai Veloster Turbo T-GDi, TCi GDi 2012+
Elantra GT Sport 2018+
IS300 2000-2004
GS300 Non-V8 1997-2005
Miata 2006 +
Mazdaspeed 3
Mazdaspeed Protégé
Mazdaspeed Miata
RX8 (All)
RX-7 Turbo II
3 Touring and Sport 2013-2018
Cooper S
Sterion ESI-R 1987-1989
300ZX Turbo 1983-1989
Sentra 2013+
Sentra Nismo 2017+
Solstice 2006-10
Boxster (Non S) 1996-2004
968 1992-1995
944 1982-2991
  944 S2 1989-1999
  911 C4 1989-1994
  9-3 ARC 2003-2005
  9-3 Aero 2.8T 2002-2014
  Sky 2006-10
SVX 1991-96
Celica GTS 1999-2006
Camry SE 2017+
  Golf VR6 1997-2003
Golf GTI 2003+
Jetta GLI 2011+
Jetta S 2011-2019
Rabbit 2.5S 2006+
C30 T5 2007-2013

  E30 (Non-M)
  Z3 1.9 1995-2002
  2002 Base 1966-1977
  Sonic 2012+
  240z/260z/280z 1970-1978
Neon - Naturally Aspirated
Charger (All) 1981-1987
Fiesta 2008 -2012
ZX2 1997-2003
Civic/CRX/Del Sol 1972-1991
Civic EX 1992-2000
Accord 1990-1993
Fit 2014+
Prelude 1978-01
Hyundai Veloster Gamma 1.6 GDi 2012+
Miata (Naturally Aspirated) 1990-2005
Spec Miata
RX-7 (1979-1991, Not Otherwise Classed)
Protege MP3
Protege 1998-2003
3i 2008-2012
MGB, MGB GT 1962-1980
Cooper (Naturally Aspirated)
Mirage 2012+
240SX SE 1989-1999
924 and 924S 1976-1988
Impreza 1992 - 2001
Legacy L FWD 1993-1999
Swift GT 1989-1994
MR2 (Naturally Aspirated)
Spitfire 1974-1980

Tuner Category Authorized Modifications

These are the Authorized Modifications for Tuner Category vehicles (i.e., what you can do to your car and have it stay in Tuner Category). Tuner Category, along with Sport, Prepped and Max. are restricted rulesets. If a modification is not specifically authorized in these Rules, it is not allowed. (If it doesn't say you can, you can’t.)

The first section outlines the Tuner Category philosophy, safety minimums, vehicle eligibility and general modification rules. Following that, the individual sections outline what you can do with each system. (e.g., body, engine, suspension, etc.)

Each set of allowances is broken down into two parts, the first of which are the "Layman's Terms." These are a basic way to describe the intent and allowance. For the rules nerds in our midst, or those who think their modification might be close to OK but not quite sure, there will be a link to the full text rules which fully explains what is allowed.

In Tuner Category, a vehicle may have every modification allowed in Sport Category, plus the modifications listed here.

1. Tuner Category Overview

The Tuner Category is meant for street-driven cars with bolt-on modifications that offer a degree of adjustability. Vehicle modifications are meant to fit between the current Sport and Max Categories, providing a natural competition outlet for auto enthusiasts using sports cars and sedans equipped with common suspension and engine modifications compatible with street use.

Modifications must still be bolt-on modifications; in most cases bolting to the OE locations, but different from Sport Category these parts may be more "tunable." Items like adjustable ride-height coilovers, more complex sway bars and, for some cars, ECU hardware changes are allowed. Suspension geometry-altering items like bump-steer correction or roll-center correction kits will not be allowed. As this is a street car, aftermarket aero items such as wings, splitters, spoilers and diffusers will not be allowed.

Tuner Category is a restricted ruleset. If a modification is not specifically authorized in these Rules, it is not allowed. (If it doesn’t say you can, you can’t.)

1. Vehicles running in Sport, Tuner, Prepped and Max Categories must meet Safety Level 1 Standards.

A. Roll bars, cages, racing harnesses and other safety equipment may be added, and must meet manufacturers' guidelines for installation. It is highly recommended that they at least meet the minimum for Safety Level 2 or Safety Level 3 Standards.

B. Nothing in the rules prevents you from adding safety equipment; the minimum amount of modification to install safety equipment is allowed.

C. To facilitate safety, vehicles that have an added roll bar may remove carpet, seats and trim (including convertible tops) behind the front seats. Vehicles that have an added roll cage may remove carpet, seats and trim (including convertible tops) other than the dash.

2. Fuel cells may be used in cars with the following restrictions and allowances:

A. OE lines may be replaced in conjunction with a fuel cell provided they are shielded.

B. Any fuel lines—including gauge and vent lines—that pass into or through the driver/passenger compartment, shall be of steel tube or metal braided hoses or bulkheaded.

C. Drivers of cars with modified or replaced OE fuel lines or tanks must wear a suit, shoes, gloves and underwear as specified in SCCA Time Trials Safety Level 2 Standards.

D. Vehicles with modified or replaced OE fuel lines or tanks must have an on-board fire suppression (fire bottle or system) meeting SCCA Time Trials Safety Level 2 Standards.

E. Participants are cautioned that this is not an allowance to maximize fuel delivery by installing higher-performance parts than authorized by category rules. (E.g., installing an upgraded fuel pump if it's not otherwise allowed.)

1. To be eligible for Sport Category:

A. A minimum of 1,000 of that model must have been produced that model year for road use.

B. The vehicle must be capable of being licensed for normal road use in North America and delivered through the manufacturer's North American retail sales outlets.

The following items are guidelines for general repair and modifications in Sport and Tuner Categories:

A. Other than when necessary for safety enhancements, you may not perform an otherwise unlisted modification in order to facilitate a permitted one.

B. Any part which becomes partially or completely detached during on-track sessions must be fixed and inspected by officials before that vehicle can return to the track. If the part is an aerodynamic addition, the part shall be completely removed for the remainder of the competition.

C. Parts (other than brakes and fluids) are not permitted to be replaced or changed after the car has passed tech inspection unless an Event Official has determined the part to be unsafe or broken badly enough that not changing it would keep the participant from the event.

D. Expendable replacement parts (e.g., bearings, seals, gaskets, filters, belts, bolts, bulbs, batteries, clutch discs, pressure plates, suspension bushings, drivetrain mounts, fenders, trim pieces, fuel filler caps, electrical sensors, etc.) may be used provided they are essentially identical to the standard parts (e.g., have the same type, size, hardness, weight, material, specifications, etc.), are used in the same location, and provide no performance benefit. These allowances are strictly to allow components to be replaced from alternate sources other than the original manufacturer. They should not be construed as an allowance to replace components with those which could be considered a “higher performance” alternative.

E. Any repairs must comply with factory-authorized methods and procedures, or industry standard methods, as follows: If the OE does not provide an appropriate method of repair, industry standard methods and procedures may be used. Such repairs may not result in a part or combination of parts that provides a competitive advantage (e.g., significant change to weight, suspension control, power, etc.) as compared to the standard part(s). Competitors are strongly cautioned to use this allowance to make common-sense repairs only. It is not permitted to use non-compliant parts even if they have been set to OE specifications.

F. Except for authorized modifications, other modifications or equipment will place the car in higher levels as appropriate. Configurations involving damaged parts (e.g., blown fuses) are not typically authorized by the manufacturer and hence are not allowed.

G. Vehicles may be street-driven cars, and SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.

2. Tuner Category - Interior and Bodywork

You can add or take away anything allowed in Sport Category. This means you can add cosmetic items that don’t make the car any lighter and have little to no effect on performance, and you can replace the driver and passenger seats with full size/upholstered seats. 

In addition, you can change any steering wheel (as long as it stays close in size) and drill holes for your remote-reservoir shocks.

Also here - you are not limited to Sport Category short-shift kit rules, you may now change the entire linkage.

As with Sport Category, you can still take advantage of the “safety loophole.” If you add a roll bar meeting Safety Level 2 Standards, you can remove carpet and trim (convertible tops included) from behind the driver and passenger seats and even replace an airbag-equipped steering wheel. If you install a full cage meeting Safety Level 3 Standards, you can remove all the trim and carpet other than the dash.

1. A hole may be added through the bodywork to route a remote reservoir for shocks/struts and hose to a remote mounting location. Such holes may serve no other purpose.

2. Any steering wheel may be used. An alternate steering wheel assembly—including all mounting hardware—which replaces an airbag-equipped wheel is not required to have an airbag. An alternate wheel is not required to have a horn button.

3. Any shift linkage may be used.

1. Accessories, gauges, indicators, lights and other appearance, comfort and convenience modifications including pedal cover kits, alternate shift knobs and paddles which have little or no effect on performance and/or handling and do not materially reduce the weight of the car are permitted. Delayed shutdown devices such as a “turbo timer,” which perform no function while the car is in motion, are permitted. This does permit the installation of an additional mirror (e.g., Wink®). The addition of small holes for attachment hardware for cosmetic modifications is implicit (e.g., holes for fasteners to mount additional gauges).

2. The driver and front passenger seats may be replaced with the following restrictions.

A. The seating surface must be fully upholstered.

B. The top of the seat, or an attached headrest, may not be below the center of the driver’s head.

C. The seat shall be securely mounted, so as to provide fore/aft and lateral support.

D. Passenger seat must be either OE or match the requirements for the driver’s seat.

3. Alternate steering wheels are allowed, provided the outside diameter is not changed by more than 1-inch from the standard size. Steering wheels with an integral airbag may not be changed unless Safety Levels 2 or 3 Standards are met.

4. Short shift kits which only change the length of the shift rod attached to the gear shift knob may be installed. Kits which change other linkage, mounting brackets and/or tension through springs are expressly disallowed.

5. A hole may be added to interior body panels, the engine compartment, the trunk, and/or a strut bar to provide access to the adjustment mechanism on a shock absorber. The hole may serve no other purpose and may not be added through the exterior body panels.

6. Any item that cannot be held permanently in place by factory-installed fasteners may be removed.

7. Spare tires, tools and jacks may be removed. Any fastening hardware and/or other pieces that can no longer be firmly secured in the absence of the spare tire may be removed, if necessary, to ensure compliance with safety inspection requirements.

8. Data acquisition systems (including video cameras) and the accompanying sensors are allowed but may serve no other purpose during a run than real-time display and data recording.

9. The removal of interior carpet, trim and seats is allowed in conjunction with the addition of safety equipment, with the following restrictions.

A. Rear seats, carpet and trim behind the front seats may be removed if the vehicle is equipped with a 4-point roll bar, driver’s seat, and restraints meeting SCCA Time Trials Safety Level 2 Standards.

B. All interior carpet, trim and passenger seats other than the factory dash may be removed if the vehicle is equipped with a minimum 6-point roll cage, driver’s seat and restraints meeting SCCA Time Trials Safety Level 3 Standards.

C. Airbags may be removed if either of the above safety levels are met.

D. Airbag-equipped steering wheels may be replaced or have the airbag removed if either of the above safety levels are met.

E. Convertible soft tops and related structure and brackets may be removed as part of this allowance.

You can do anything allowed in Sport Category, so there are a few allowances there including some trim-level bodywork swaps.

In addition to Sport Category allowances, you can also remove rub strips, replace pop-up headlights, add/replace tow hooks and roll your fenders.

1. Front hoods, engine covers, trunk lids and hatches not containing glass, front fenders, rear fenders not part of chassis structure (unibody), front and rear bodywork, and side skirts may be replaced with factory parts or exact duplicates in order to facilitate allowed modifications.

2. Factory rub strips may be removed.

3. OE “pop-up” headlights may be replaced with static headlights, provided the replacement units are intended for automobile use on public roads as a primary means of illumination, and retain high and low beams as originally provided by the manufacturer. Minor repositioning of the headlights can accommodate the alternate headlight, but the unit may not be relocated, and the repositioning may serve no other purpose. All associated hardware may be removed, replaced or modified.

4. Bolt-on tow hooks and tie downs may be modified or replaced. Addition of tow hooks and tie downs are permitted, and location is unrestricted. Non-standard tow hooks shall serve no other function.

5. Fenders may be rolled, but no material may be added or removed.

1. Addition or removal of spoilers, splitters, rear wings, bumper covers, valances, side skirts, convertible hard tops and scoops/vents is allowed provided that:

A. The removal of parts matches a production model of that generation classed in Sport Category. (eg., You may not remove parts unless a model of that vehicle was available without the part or parts.)

B. It is a production part which is standard or optional equipment of a model of the vehicle classed in Sport Category.

C. It is listed in the vehicle manufacturer’s accessory catalog for that vehicle for normal highway use. This may not allow for parts sold through a manufacturer’s performance catalog (e.g., Ford Racing, HPD, Mazdaspeed, Mopar Performance, Mugen, NISMO, SPT, TRD, etc.).

D. All allowed parts must be installed as directed by the manufacturer. Exact replicas, including weight, from alternate sources are also permitted.

E. Updated parts, replacement parts, or any other changes by the manufacturer documented in the parts catalog or other manufacturer documentation as superseding the original part number used when manufactured are considered to be standard parts.

2. Factory emblems, mud flaps, bolt-on front valance lips/spoilers and fog lights (except those integral to a headlight or turn signal) may be removed. Rear wings may be removed so long as the vehicle retains any federally-mandated third brake light.

3. Hood straps or fasteners may be added.

4. Cars may add one (1) rear trailer hitch. The resulting weight addition is allowed. The hitch may serve no other purpose. Factory tie downs and cosmetic pieces (e.g., diffusers) may be modified or removed to facilitate hitch installation. Complete or partial removal of the hitch is allowed for competition, provided it does not result in a reduction in weight compared to the unmodified standard configuration.

5. Tow bar brackets may be installed but may serve no other purpose.

3. Tuner Category - Wheels and Tires

Just like in Sport Category you can use any wheel, including composite wheels (as long as they pass safety inspections). However in Tuner Category, there is no minimum weight, so you can use those ultra-light wheels to your heart's content.

1. Any width or diameter wheel and wheel spacers may be used provided it complies with the following:

A. Non-metallic wheels must be certified/approved from an appropriate, recognized standards organization. (e.g., FIA, SFI, SAE, TUV, etc.)

B. Wheel spacers are permitted.

C. Wheel studs, lug nuts, valve stems (including pressure-relief types) and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts, but the number of fasteners may not be changed.

D. Tire pressure monitoring sensors may be removed.

E. Centerlock/spline drive/knock-off type hubs may be converted to lug-type hubs.

2. There are no wheel weight restrictions in Tuner Category.

1. Any width or diameter wheel and wheel spacers may be used provided it complies with the following:

A. Non-metallic wheels must be certified/approved from an appropriate, recognized standards organization. (e.g., FIA, SFI, SAE, TUV, etc.)

B. Wheel spacers are permitted.

C. Wheel studs, lug nuts, valve stems (including pressure-relief types) and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts, but the number of fasteners may not be changed.

D. Tire pressure monitoring sensors may be removed.

E. Centerlock/spline drive/knock-off type hubs may be converted to lug-type hubs.

F. Aftermarket, accessory-catalog or non-standard OE wheels shall meet the minimum wheel weights determined by the following formula and multiplier.

(Diameter + Width) x Multiplier

15-inch Wheels

(Diameter + Width) * 0.48

16 and 17-inch Wheels

(Diameter + Width) * 0.58

18-inch Wheels

(Diameter + Width) * 0.65

19 and 20-inch Wheels

(Diameter + Width) * 0.77

Example: For a 15-inch diameter by 7.5-inch width (15x7.5) wheel: 15 + 7.5 = 22.5, then multiply 22.5 x 0.48 which = minimum weight of 10.8 lbs. for any 15x7.5-inch wheel.

Tires still have to be 200 treadwear or higher, but Tuner Category has a different set of width restrictions.

1. Tires must meet the eligibility requirements of the Sport Category, but do not have to meet Sport Category width limits.

2. Tuner Tire Width Limits

Tires shall have a section width up to and including the following (mm):




Tuner 1 (T1)

2-Wheel Drive





Tuner 2 (T2)

2-Wheel Drive



All-Wheel Drive


Tuner 3 (T3)

2-Wheel Drive



All-Wheel Drive


Tuner 4 (T4)

2-Wheel Drive



All-Wheel Drive


Tuner 5 (T5)

2-Wheel Drive



All-Wheel Drive


3. Cars in Tuner Classes 2–5 and are otherwise legal for Tuner Category may bump up classes based on tire size. Cars in Tuner 1 with oversized tires will go into their appropriate Prepped or Max Category class.

Tires must meet the following requirements to be eligible for use in Sport Category. No tire model will be eligible for Time Trials competition until it meets all requirements of this section. Tire models not meeting the requirements by April 30 are not eligible for Time Trials competition until after the Time Trials National Championships of the year.

1. Specification

A. Minimum UTQG Treadwear Grade of 200.

B. Minimum molded tread depth of 7/32 inch as specified by the manufacturer.

C. Listed in a current year or prior two years of the “Tire Guide®” and/or the “Tread Design Guide®” (

D. US Department of Transportation (DOT) approval.

E. Tires must be designed for highway use on passenger cars.

2. Eligibility Requirements:
The following are prerequisites before a tire can be used in competition at Time Trials Events.

A. Tire availability: Tires are considered available when competitors can take possession through retail channels. Pre-orders are not considered available.

B. Tires must be equally available to all competitors. Tires that are in short supply do not specifically violate this section. Extensive shortages may result in the tire being placed on the exclusion list until supply is replenished. Tire variations differing from standard specification, delivered only on a limited basis, or only to selected competitors may not be used.

C. Tire models must have tires available in at least four (4) rim diameters and in at least six (6) sizes which meet these requirements.

D. Material Change: Tires which previously met the eligibility requirements that undergo a significant compound change, tread pattern change, or other significant redesign reset the requirement for eligibility described in this section.

E. A tire model which was previously allowed by these rules continues to be eligible for competition until specifically disallowed.

F. Reintroduction: Models that were once discontinued will be considered a new model once reintroduced and must meet all the requirements of this section.

3. Tire Size Limits
Tires are limited to the OE section width, or have a section width up to and including the following (mm):




Sport 1 (S1)

2-Wheel Drive





Sport 2 (S2)

2-Wheel Drive



All-Wheel Drive


Sport 3 (S3)

2-Wheel Drive



All-Wheel Drive


Sport 4 (S4)

2-Wheel Drive



All-Wheel Drive


Sport 5 (S5)

2-Wheel Drive



All-Wheel Drive


Sport 6 (S6)

2-Wheel Drive



All-Wheel Drive


Cars in Classes 2–6 and are otherwise legal for Sport Category may bump up classes based on tire size. Cars in Sport 1 with oversized tires will go into their vehicle appropriate Tuner Category class.

4. Tire Use
Unless a “wet session” is declared by event officials, vehicles must run on the same set of tires for all competition rounds, and the tires should be marked with a stamp on grid of the first competition. Tires may also be replaced at the discretion of the Technical Chief in cases safety issues such as damage or excessive wear. (Entrants are warned that damage caused by deliberate abusive handling or deliberate shaving should not be given a replacement allowance.)

5. Other

A. Tires may be shaved evenly and parallel to the axis of rotation, but may not otherwise be siped, grooved or modified.

B. Tires must have a minimum tread depth of 2/32nds at two (2) points 180 degrees apart.

C. No recap and/or retread tires may be used.

D. Excluded tires: Tires may be excluded for, but not limited to, low volume production, extensive availability limitations and specialty design.

E. The tire must not appear on the following exclusion list, which may be altered at any time by the Time Trials Board (TTB) upon notification of membership.

- Kumho V720 ACR (less than minimum molded tread depth)

4. Tuner Category - Brakes

You can do everything you're allowed to do in Sport Category (like cross-drilled/slotted rotors, or OE brake option packages). You're also allowed to install "big brake kits" and add ducting to help keep them cool.

1. Non-standard brake rotors may be used provided they are of equal or larger dimensions.

2. Aluminum rotor hats are allowed.

3. Cars originally equipped with solid (non-vented) rotors may utilize vented rotors.

4. Brake calipers and mounting brackets may be replaced provided they bolt to the standard locations and the number of pistons is equal to or greater than standard. A functioning emergency brake of the same type, operation, and actuation as OE must be present. Drum brakes may be replaced with disc brakes of a diameter equal to or greater than the inside diameter of the standard drum. Such conversions must be bolted, not welded, to the axle/trailing arm/upright and must include an integral, redundant emergency brake. Changes to backing plates/dust shields/brake lines to accommodate these changes are permitted but may serve no other purpose.

5. Air ducts may be fitted to the brakes and changes may be made made in the body/structure for their use. Ducts or holes may serve no other purpose. Backing plates and dirt shields may be modified or removed.

1. The make and material of brake pad/shoe linings (friction material) may be changed.

2. Non-standard brake rotors may be used provided they are of equal or larger dimensions (diameter and thickness) and match the OE design and are constructed of the OE or heavier materials. Thickness includes the individual plates of a vented rotor, as well as the overall dimension. The diameter for replacement rotors is measured at the minimum outside dimension. Cross-drilled and/or slotted brake rotors may be fitted provided all such voids are within the disc area and comprise no more than 10% of that area.

3. Brake lines may be substituted with alternate DOT-approved flexible brake lines.

4. Alternate brake bleeder fittings (e.g., Speedbleeders®) are permitted. They may serve no other purpose.

5. Standard anti-lock braking systems (ABS) may be electrically disabled but may not be removed or altered in any other way.

6. Brake Rotors and Calipers may be swapped to OE option package configurations from the same model and generation of car, providing the rotor width and diameter are of equal or larger sizes and the number of caliper pistons is the equal or greater. The allowances from 1–5 also apply to option package swaps.

5. Tuner Category - Steering and Suspension

You can replace steering rack bushings, as long as they stay the OE material (i.e., rubber).

Steering rack bushings may be replaced but must attach in the factory location(s) without additional modification or changes. Steering rack position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited. This does not allow shimming or otherwise relocating the steering rack.

The Tuner Category Rules allow you to replace your stock shocks and struts with most shocks or struts which bolt to the stock places and don't alter suspension geometry. (This mean's threaded-body coilovers are OK, as well as remote reservoirs and more than one adjustment.)

There are also some allowances for converting to a spring/shock assembly for cars that had the spring separate from the shock.

1. Shocks and Strut Replacement Allowances:

A. Any shock absorbers may be used.

B. Shock absorber mounting brackets which serve no other purpose may be altered, added, or replaced, provided that the attachment points on the body/frame/subframe/chassis/suspension member are not altered. This installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed.

C. The number of shock absorbers shall be the same as standard.

D. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment.

E. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.

2. The following additional allowances apply to cars originally equipped with separate spring and shock absorber assemblies.

A. Coil springs may be relocated so they encircle the body of the shock absorber in a “coilover” configuration.

B. Coil spring perches may be modified, added, or replaced and their position may be adjustable.

C. Additional bolt holes may be drilled for coilover assembly mounting brackets. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.

Sport Category vehicles may use any springs that fit the rules. There are no limits on where to get the spring from as there are in Sport Category.

Springs must be of the same type as the original (e.g., coil, leaf, torsion bar, bellows) and except as noted herein, must use the original spring attachment points. This permits multiple springs, if they use the original mount locations. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered and their position may be adjustable. Spacers are allowed above or below the spring. Coil springs may incorporate spring rubbers. Suspension bump stops may be altered or removed.

You can add any sway bar, including fancy splined ones that don't directly replace the OE sway bars.

Substitution or removal of sway bars (at one or both ends of the car) and supporting hardware (brackets, end links, bushings, etc.) is permitted. Tow hooks may be removed for the instillation of sway bars.

You can install a 2-point strut brace if there were no strut braces, or replace a 2-point with a 2-point, or replace a 3-point with a 3-point. There are also allowances for strut braces on the underside of the car, and some attachment rules.

Strut bars are permitted with all types of suspension, subject to the following constraints:

1. A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.

2. A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.

3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2 inches (50.8mm) in any direction of the actual suspension attachment to the chassis.

4. Except for standard parts, no connections to other components are permitted. Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.

As part of Tuner Category, this is where much of the “tuning” comes in. Here you can change ride height through suspension adjustments and some other items, you can replace suspension bushings, if you keep the ratio of rubber to metal the same. You can also install either camber plates, or camber bolts, or adjustable control arms—but not more than one of them. We also let you replace a non-adjustable arm with one that doesn’t move, if it’s available at the Tire Rack or on the list below.

For the rear-wheel-drive folks in Tuner Category, we have some allowances just for you as well; things like traction bars, stabilizers, Panhard rods and differential covers.

This one has some complication to it, so if you’re really getting crazy with suspension, it’ll pay to give the full rules a good look.

1. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers that alter suspension geometry, such as those between the hub carrier and lower suspension arm.

2. Suspension bushings may be replaced with bushings of any materials (except metal) if they fit in the original location. Offset bushings may be used. In a replacement bushing, the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (e.g., ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position.

3. The following allowances apply to strut-type suspensions. Adjustable camber plates may be installed at the top of the strut and the original upper mounting holes may be slotted. The drilling of holes to perform the installation is permitted. The center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.

4. Camber bolts may be installed providing these parts use the original, unmodified mounting points and meet the restrictions specified in Sport Category. Caster changes resulting from the use of camber bolts are permitted.

5. Camber kits (also known as camber compensators) may be installed. These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:

A. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be adjustable, but not both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced, changed, or modified.

B. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be adjustable OR other methods of camber adjustment as allowed by the previous sections may be used, but NOT both.

C. The non-adjusting control arms for vehicles having integral bushing/arm assemblies may be replaced subject to the following restrictions.

a. Arm length must remain the same as OE.

b. The part may not be adjustable.

c. The replacement arms must attach to the original standard mounting points. All bushings must meet the requirements of this section. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.

d. Any allowed arm must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order. Parts do not have to be sourced from Tire Rack, but they must be as they would have come off the shelf there, or the part must be on a specific approval list.

e. If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not available at Tire Rack you may write in for specific approval of that brand and model.

6. On swing or trailing arm suspensions, the main arms may not be modified or replaced, but lateral locating links/arms may be modified or replaced.

7. Front wheel drive (FWD) cars with rear beam axles may use shims between the rear axle and hubs.

8. The replacement arms or mounts must attach to the original standard mounting points. All bushings must meet the requirements of Tuner Category Rules. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm, except as incidental to the camber adjustment. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.

9. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

Note: Many modern suspension designs known by other names, actually function as double A–arm designs. These include the rear suspensions on 1988-on Honda Civic/Integra, Chrysler/Plymouth/Dodge Neon, BMW E36, and most “multi-link” and are covered by the double/unequal arm rule.

10. On strut-equipped cars, the strut’s lower integral mounting bracket, for attachment to the upright or spindle, is unrestricted provided it attaches to the standard location. Any resulting change to the position of the strut centerline is allowed. Such brackets shall serve no other purpose. This does not allow for changes to the integral steering arm on cars that have the steering arm integrated with the strut body.

11. Changes in alignment parameters that result directly from the use of the allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing that meets the restrictions of Tuner Category Rules are allowed, including those resulting from a change in the pivoting action to:

A. About the mounting bolt, or

B. About the bushing itself.

12. Subframe mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Subframe position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited.

13. The following list is Solid Axle Rear Wheel Drive (RWD) Suspension Allowances:

A. Addition or replacement of suspension stabilizers (linkage connecting the axle housing or De Deion to the chassis, which controls lateral suspension location) is permitted.

B. Traction bars or torque arms may be added or replaced.

C. A Panhard rod may be added or replaced.

D. The upper arm(s) may be removed, replaced, or modified and the upper pickup points on the rear axle housing may be relocated.

E. The lower arms may be replaced or modified and the lower pickup points on the rear axle housing may be relocated.

F. Differential covers and attaching hardware may be replaced.

G. Methods of attachment and attachment points are unrestricted but may serve no other purpose (e.g., chassis stiffening). This does not authorize removal of a welded-on part of a subframe to accommodate the installation.

The following non-adjustable control arms not available at Tire Rack are allowed in SCCA Time Trials Tuner Category:

There are no models listed at this time.

You are allowed sub frame connectors (SFCs) that run front-to-back, but there are some rules on installations. For instance, you can drill for mounting bolts, but you can't weld them in or cut subframes or unibody.

Longitudinal (fore-aft) subframe connectors (SFCs) are permitted with the following restrictions:

1. They must only connect previously unconnected boxed frame rails on unibody vehicles.

2. Each SFC must attach at no more than three (3) points on the unibody (e.g., front, rear, and one point in between such as a seat mount brace or rocker box brace).

3. SFCs must be bolted in place and not welded.

4. No cutting of OE subframes or floorpan stampings is permitted. Drilling is permitted for mounting bolts only.

5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment. No alteration to the OE components is permitted.

6. SFCs may not be used to attach other components (including but not limited to torque arm front mounts or driveshaft loops) and may serve no other purpose.

6. Tuner Category - Electrical

In addition to everything allowed in Sport Category like spark plugs, spark plug wires and grounding cables, Tuner Category allows you to replace your battery—even to a lightweight one—and relocate it if you want. Of course, this doesn't apply to electric or hybrid cars, because we're pretty sure that would get out of hand! You can also replace the alternator and install things like electric fans.

Read the full rules to see details on things like cables and making sure it's all done safe.

Except for those with electric and hybrid powertrains, Tuner Category vehicles may do everything allowed in Sport Category plus the list below.

1. OE traction control systems may be electrically disabled, but not removed or altered in any other way.

2. The make, model number and size of the battery may be changed, but not its voltage.

3. Relocation of the battery or batteries is permitted but not into the passenger compartment. If the battery is relocated and the original battery tray can be removed by simply unbolting it, the tray may be removed or relocated with the battery. Holes may be drilled for mounting or passage of cables. Longer or shorter cables may be substituted to permit relocation.

4. The number of battery or batteries may not be changed from standard. The area behind the rearmost seat is not considered to be within the passenger compartment. The area under the rearmost seat is within the passenger compartment.

5. Holes may be drilled in the firewall to permit passage of electrical wiring. It should be no larger than necessary to facilitate allowed modifications in this section and shall serve no other purpose.

6. Any starter, generator or alternator may be used in the original position. An alternator or generator must have an electrical output (including amperage) equal to or greater than the original equipment unit. Any generator or alternator pulley and belt of the same type as standard may be used.

7. Electrically driven fans are allowed. Flex fans are not allowed.

1. The make of spark plugs, points, ignition coil and high-tension wires is unrestricted including spark plug wires having an in-line capacitor. Substitution or addition of ignition coil mounting brackets is permitted, provided they affix to the original standard location and serve no other purpose. (Modification of the distributor cap for the purpose of installing allowed non-standard components is not permitted.)

2. On cars made prior to January 1, 1968, any ignition system using a standard distributor without modification may be used.

3. Ignition settings may not be mechanically adjusted outside factory specifications.

4. Additional battery hold-down hardware may be added to supplement the standard equipment in order to meet safety inspection requirements. It may serve no other purpose.

5. Tire pressure monitoring systems (TPMS) may be disabled. Altering the signal to the TPMS is permitted.

6. On cars without the ability to turn off anti-lock braking systems (ABS), electronic stability control and/or traction control (ESC/TC) from the manufacturer, modifications to defeat the ABS/ESC/TC are permitted. These modifications are limited to altering the inputs to the ABS/ESC/TC processor (e.g., removing fuses, unplugging yaw or steering angle sensors, altering signals, etc.) and may serve no other purpose. Any codes or error lights resulting from ABS/ESC/TC modifications are permitted.

7. On cars equipped with computer-aided gear selection or “skip-shift” features from the manufacturer, modifications to defeat the skip-shift feature are permitted any may serve no other purpose.

8. On cars with electronically-controlled exhaust pipe valving downstream of the catalytic converter, devices may be added to satisfy the PCM/ECU provided the OE component is still installed. Such devices shall perform no other function.

9. The addition of electrical grounding cables and associated distribution blocks/terminals is permitted. Holes may be drilled for mounting only. This does not permit the use of electrical enhancement components such as condensers, voltage controllers, etc.

7. Tuner Category - Engine and Drivetrain

All the stuff in Sport Category is still allowed. In Tuner, you can reflash the ECU just like you can in Sport Category and add a fuel pressure regulator. For cars 1995 and older, you can now run a standalone ECU, or chip your OE ECU, or add a piggyback.

For forced induction cars, you can run a manual/mechanical boost controller in Tuner Category.

In addition to the Sport Category allowed modifications, the following modifications may be made to Tuner Category ECU/engine controls:

1. For all model years, the following allowances apply:

A. The standard PCM/ECU may be re-programmed without restriction.

B. Fuel pressure regulator(s) may be replaced in lieu of electronic hardware or software alterations. It is not permitted to mechanically alter the fuel pressure regulation AND make other hardware or software changes to engine operation.

C. Ignition timing may be set at any point on factory-adjustable distributor ignition systems.

D. Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed.

2. 1995 and older vehicles, in addition, may replace the standard PCM/ECU without restriction.

3. Boost may be controlled through a mechanical boost controller.

1. OE traction control systems may be electrically disabled, but not removed or altered in any other way.

2. The engine management system parameters and operation of internal combustion engines may be modified only via the methods listed below.

A. OE ECU software may be reprogramed, but no changes to the factory ECU hardware are permitted.

B. Any OE OBD2 or newer communications port functionality must remain.

C. The Check Engine Light (CEL) or Malfunction Indicator Light (MIL) may be disabled via software.

D. Only OE sensors may be used for engine management.

E. Ignition timing may be set at any point on factory adjustable distributor ignition systems.

Everything from Sport Category is legal, but now forced induction cars can add or replace an intercooler. Only the minimal mount of trimming can be done to install it though, so if you get too fancy with openings and such, it's off to Max you go!

As utilized only on engines originally equipped with forced induction, induction charge heat exchangers (also known as “intercoolers” or “charge air coolers” [CACs]) are unrestricted in size and configuration and are subject to the following restrictions: 

1. Air-to-air CACs and radiators for air-to-liquid CACs must be cooled only by the atmosphere except for standard parts.

2. Body panels, fascias, or structural members may not be cut or altered to facilitate CAC installation.

1. The air intake system up to, but not including, the engine inlet may be modified or replaced.

A. The engine inlet is the throttle body, carburetor, compressor inlet, or intake manifold, whichever comes first relative to the intake flow.

B. The existing structure of the car may not be modified for the passage of ducting from the air cleaner to the engine inlet. Holes may be drilled for mounting.

C. Emissions or engine management components in the air intake system, such as a PCV valve or mass airflow sensor, may not be removed, modified, or replaced, and must retain their original function along the flow path.

You can replace your radiator with a larger one (but not a smaller one) as long as it goes in the stock locations and uses the stock mounts. You can also add water overflow tanks (called expansion tanks).

1. Engine cooling radiators may be replaced or added with alternate parts subject to the following restrictions:

A. Radiator core dimensions (width, height, thickness) cannot be smaller than the standard part.

B. Radiator must mount to OE radiator mounts.

C. Fluid capacity and dry weight of the radiator must be no less than that of the standard part. Installation of an alternate radiator may serve no other purpose (e.g., to allow a cold air intake passage).

D. The installation of water expansion tanks is allowed. A water expansion tank is the container which catches overflow coolant.

E. Thermostats may be added or substituted. A thermostat is a device which controls the passage of water.

F. Modifications necessary for additional radiators must be the minimum required for installation.

You can rebuild the engine, but you have to stay within tight factory service limits. If you're going to rebuild your engine, or your engine has been rebuilt, give the full Rules a look.

1. Engine Service Limits

A. Engines may be rebored to the manufacturer’s first standard overbore, not to exceed 0.020 inch (0.508 mm). Sleeving is allowed to repair to the standard bore. Only OE-type standard or first overbore pistons of the same configuration and of the same or greater weights are permitted. No interchange between cast and forged pistons is allowed.

B. Valve seats and guides in older engines originally designed for leaded fuel may be only substituted with alternate components if the dimensions are the same as those of the standard components.

All the stuff that was approved in Sport Category, plus in Tuner Category, you can have mechanical Limited Slip Differentials (LSD), and replace final drive ring and pinions with alternate parts as long as the final drive ratio isn't changed from OE.

You can also use an aftermarket pressure plate and clutch disk as long as they are both the same diameter and design as stock; so no multi-puck clutches unless your car came with it from the factory. You can replace the flywheel as long as the diameter and material are the same, so you can't put an aluminum flywheel in place of a steel one.

Differential bushings can now be replaced, as long as they are the same material as stock (solid metal is a no-no).

1. Limited Slip Differentials (LSD): Any mechanical LSD unit is permitted. Final drive ring and pinion gears may be replaced with alternate parts, provided the final drive does not change.

2. Any mechanical shift linkage may be used.

3. Any clutch disc and pressure plate of stock diameter and design may be used, provided that they can be bolted directly to an unmodified stock flywheel.

4. Alternate flywheels are permitted. Flywheel material shall be the same type as OE and the ring gear diameter must be the same as the OE flywheel.

5. Differential mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Differential position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited.

1. Transmission and differential coolers and lines may be added.

2. Shifter bushings may be replaced; non-metal bushings may not be replaced with metal bushings.

In Tuner Category, you can do anything you can in Sport Category, but now you can also replace the header, down pipes. The Catalytic Converter can be replaced, but there are limits on what you can do and where you can put it.

Remember though, making sure it is safely installed and you stay in line with federal laws and track noise limits is up to you.

1. Exhaust manifolds, headers, downpipes, and associated EGR tubes may be replaced with alternate units. Exhaust exit may be relocated provided it meets safety requirements. Relocation of the oxygen sensor on the header is permitted. Exhaust heat shields which cover only, and attach solely to, these parts may also be replaced, removed, or modified. All other exhaust heat shields may be modified the minimum amount necessary to accommodate allowed alternate exhaust components. Mounting brackets/hardware which serve no other purpose are considered part of the exhaust components.

2. Catalytic converters – Any catalytic converters are allowed, provided they meet the following restrictions.

A. Catalytic converters must attach within 18” (457.2 mm) of the original unit.

B. Multiple catalytic converters may be replaced by a single unit.

C. The inlet of the single replacement converter may be located no further downstream than 18” (457.2 mm) along the piping flow path from the original exit of the final OE converter.

D. The extents of an OE converter are defined by the expansion chamber in which the catalyst is contained, regardless of placement within larger exhaust sections.

E. Replacement converters must have a minimum catalyst density of 100 cells per inch and minimum substrate length of 3” (76.2 mm).

Note: The SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.

1. Any part of the exhaust system beyond (downstream from) the last catalytic converter, if so equipped, may be substituted or removed provided the system exits the car in the original location and meets safety requirements.

2. Vehicles equipped with exhausts that exit in multiple locations may change to a single outlet in any of the original locations.

3. Stainless steel heat exchangers are permitted only if the physical dimensions and configuration remain unchanged.

4. Modifications of any type, including additions to or removal of, the catalytic converters, thermal reactors, or any other pollution control devices in the exhaust system are not allowed and the system must be operable.

5. Replacement catalytic converters must be OE if the vehicle has not exceeded the warranty period as mandated by the EPA. Converters must be of the same type and size and used in the same location as the original equipment converter(s). This does not allow for a high-performance unit. If the vehicle has exceeded the warranty period, replacement catalytic converters must be OE-type.

6. Exhaust hangers which are welded on the car are considered part of the body and may not be changed or removed.

In addition to everything you can do in Sport Category, now you can change oil pans, oil pickups, differential covers, and add fluid coolers for oil and transmission coolers.

Oil pans, oil pickups and differential covers may be modified or substituted. Addition or modification of windage trays or crankshaft scrapers is not allowed. Engine oil, transmission fluid, differential fluid and power steering fluid coolers may be added or substituted (including oil to coolant heat exchangers), but may not serve any additional purpose.

1. Any oil filter may be added if not originally equipped. Canister-type oil filters may be replaced with a spin-on type filter using a minimum amount of hardware and connecting lines.

2. Any oil or grease, including synthetic, is permitted.

3. Coolers and lines may be added for lubricating and hydraulic-type fluids (i.e. not fuel).

4. The installation of oil catch tanks or oil separators is allowed provided the function of the PCV system remains intact.

5. Cars with combustion chamber oil injection systems (such as those in rotary engines) may supplement the standard engine lubrication with additional oil supplied through the standard fuel delivery system.

You can do all the stuff from Sport Category, plus now you can do things like change the accessory pullies (crank pully, pullies for AC and power steering belts, but not timing gears, cam gears or supercharger pullies!).

Any accessory pulleys and belts of the same type (e.g., V-belt, serpentine) as standard may be used. This allowance applies to accessory pulleys only (e.g., alternator, water pump, power steering pump and crankshaft drive pulleys). It does not allow replacement, modification, or substitution of pulleys, cogs, gears or belts which are part of cam, layshaft, or ignition drive or timing systems, etc. Any crankshaft damper or pulley may be used. SFI-rated dampers are recommended. Supercharged cars may not change the effective diameter of any pulley which drives the supercharger.

1. Engine “dress-up” items such as chrome dipsticks and non-standard filler caps are permitted, provided they serve no other purpose.

2. Upper engine shields made of plastic material, the purpose of which is to hide mechanical components in the engine compartment, may be removed if they have a solely aesthetic and/or acoustic function.

3. Silicone replacement hoses are permitted as alternate components provided they meet standard parameters with regard to size, shape, location, and performance equivalence.

8. Other

When a car is out of production, or parts are no longer available, you can use aftermarket parts as long as they are as close as possible to the original specs, and are not high-performance parts.

Where a car is out of production and the manufacturer is either out of business, stocks no parts or no longer has a required part, a part of any origin but as similar as possible to the original may be substituted.

1. The entrant must be prepared to show documentary evidence that one of the three circumstances above applies and that the substituted part is as similar as possible under the circumstances.

2. Substitute parts which provide improvements in performance (e.g., superior gearing, lighter weight, better camshaft profile, etc.) are not permitted under this allowance.

9. Sport/Tuner Category - Fuel

Sport and Tuner Categories have the same fuel rules. Fuel has to be federally approved for use on public highways (no racing fuels), and you can only use E85 or the like if your vehicle owner's manual says you can. (That means you can't tune/reflash an ECU a car to run E85.)

You can run propane or natural gas if the setup is safe, and the car only runs on those types of fuels.

1. Sport and Tuner Category vehicles will use fuel which is “Federally approved for use on public highways.” This does not allow racing-type fuels which are available at service station pumps.

2. Fuels comprised of more than 15% ethanol may only be used when specified by the manufacturer (e.g., in the owner’s manual for flex-fuel vehicles).

3. Propane or Compressed Natural Gas (CNG) fuel may be used in any category provided that the following conditions are met:

A. The tank must be located in a safe location on the car and be firmly and securely mounted. This does not permit the cutting of vehicle sheet metal (e.g., the trunk floor) for tank installation.

B. The tank must conform to Federal and local container standards and have an emergency relief/cut-off control.

C. For use of propane or CNG as a fuel, no changes to the induction system of the engine may be made with the exception of the necessary fuel lines to the carburetor or fuel injection. There may also be no other engine parts changed.

D. The entire system must meet local ordinances covering the use and transmission of compressed gas.

E. Propane or CNG may not be used in combination with another fuel.