Stealth mods! So sneaky I love it! hahaha...
Shorter gearset, LSD, mild head work, high compression internals, bored out throttle body, uprated shocks =)
And they only stipulate that you can't add things to your race car, how about removing things like soand deadening material, passenger seats, carpet, linings, trims, spare wheel, aircon =D
What do you get for winning?
EDIT :
Rules do mention what you can remove.