my buddy runs 12.3's all day long with a 02 wrx(stock turbo and ic) that has almost 100000 miles on it and he has been running a 35-40 shot on his with no problems. he does however have it programed through the utec and was tuned by coastal dyno. but i would recomend professional tuning on a wrx especially if you are wanting to use a stock turbo and intercooler.