I switched exhausts on my 86 and SS, so now I have the HKS on my SS. Im a little disapointed that its a lot quieter on my SS for some reason. oh well. I love the way it looks though. Ill try to get pix up soon.
yes its only 2.5...I dont really see why Id want to go higher. Im not planning on upping the boost (or not by much if I do). It does flow better than stock though. its a nice smooth system. none of those ripples in the bends like the stock exhaust.