my buddies got an rs4 with a 13.5 in it. He doesn't race, just likes to come with me on practice days and have fun. Anyway, we have tuned the car the best we can. It is very limited in tuning. You can't adjust the rear toe for example.
Of course with the 13.5 he beats me down the straits. We just can't seem to keep his corner speed on par with my tc4 or tc5.
--pakk