Did the race a total of five times with a '99 Impreza I won in rallying. I started off with basically a stock car but in the end had and came in 5th. Ended up with 450hp-ish, trans set to 180mph, racing softs, no stability control, untuned suspension (just drop + stiffer shocks), ABS at 5, stage 1 diet. Came in 2nd. Twice.
Very challenging, getting a good clean start is the key. At the end of the day it is much less about the car and much more about knowing the track and skill, which is what it should be, which is why it is fun.
BTW, on a somewhat related note, recently had the opportunity to drive a '11 STI sedan for a week - what an awesome car, much better than the '02 WRX I used to own.