STH would be my guess, based on their definition of the catch-all car: < 2.5L forced induction 4 passenger sedan or coupe not otherwise classified (NOC). Other than the tune your car is stock. The faster cars you will be competing against will have every bolt-on known to man.
The AWD Audi TT is probably a decent car for that class since it is relatively light, can comfortably run a 265 tire, and street touring permits a stage 2 tune.