You can customize your interior so you can replace (but not remove) the carpet, seats, trim and maybe even paneling. We're not going to argue too hard if you do things like remove package trays and such, but we don't want bare interiors. Bare metal interiors are race cars. Unless you can show us a REALLY compelling reason it's done that way on your street car, we're going to consider bare metal/stripped interiors an Unlimited Category car. (It better look like the Hughes H-1 Racer in there.) "Because I like battleship grey paint" isn't a compelling reason.

Of course, if you add roll bars, you can remove all that stuff from the front seats back, and if you put a cage in, you can remove everything but the dash.