You definately did make the right choice!
Since he is stage 2... He should have about 224 whp and 271 wtq... and a stock sti should have about the same whp maybe a little more but less wtq... I think the torque is why he pulled on you early... and having a five speed over a six would mean that he would have to shift less... but your turbo is bigger for more top end... should be a pretty close race either way in my opinion... congrats on two nice cars!!