the mods and the problem he have on his z now ? so if his z is fine without any major problem, he should run mid or low 11 ? I don't think so. Yes Z06 only have 40hp more then stock C5, but look at the number improve on the 0-60 and 1/4 miles run.Can a stock TT z have 40hp increase and cut the 1/4 mile time that much ? the point is : the hp is not the only thing go fast!!