Being an enthusiast is wonderful, there are so many choices in modifications, series and formats for #funwithcars. Here is a guide to help you find where your car and particular set of modifications fits within our Rules.

1. Write down everything done to your car. Sit down with that list and your beverage of choice and start at Rules – Sport Category.

2. Start at "Interior" and click the links, comparing your list with what's allowed; make sure to remember, "if it doesn't say you CAN, you CAN'T."

Some of the major things that would move you up to Tuner Category are:

1. Ride-height adjustable shocks.
2. Headers and the removal of catalytic converters.
3. Intercoolers, supercharger pullies, mechanical boost control.
4. Standalone, chipped ECUs or ECUs with piggyback-style programming.

3. If you get all the way to the bottom and everything you did is allowed, find your car in the Sport Category classes in Step 2. If your car isn't classed or excluded, ask us to class that year, make, model and trim level using the Contact page.

4. If you did find something that your car has which isn't allowed in Sport Category, then go to Rules – Tuner Category and start the process again.

Some of the major things that would move you up to Max Category are:

1. Putting an aftermarket splitter or wing on your car.
2. Doing any internal work to your engine (cams, oversized pistons, etc.).
3. Changing the throttle body or intake manifold.
4. Swapping your engine for one that didn't come in your model and trim level car.

5. If you get to the bottom and everything you did is allowed, find your car in the Tuner Cateogry classes in Step 2. If it isn't classed or excluded, ask us to class it using the Contact page.

6. If you find something on your list that isn't allowed in Tuner, (I bet you see where this is going) go to Rules – Max Category and start at the top.

Some things that would move you up to Unlimited Category:

1. Interior carpet, seats and trim removal without adding safety equipment like a roll bar or roll cage.
2. Having "R-Compound" tires—that is any tire under 200 Treadwear—or non DOT racing tires on your car.
3. Having massive aftermarket aero like huge wings, big diffusers and large splitters.
4. Having a tube frame car, or car with huge changes to suspension geometry and construction.

7. If everything on your list is allowed in Max, then use the classing formula for the Category in Step 2 to determine your class. (We don't class individual cars here, other than the list of approved kit and reproduction cars.)

8. If you find something that isn't allowed in Max, congrats! You have a race car or a creation close enough it may as well be. You're in Unlimited Category. Read the Unlimited rules to make sure you're still good to go. (Mr. Musk we won't tell you again, you may run your Roadster in SCCA Time Trials, but not if it's attached to your SpaceX Falcon.)