My turbos were built by Turbonetics and they are pretty much exactly the same thing as the sport 500s (which are just upgraded stock turbos). Mine have the garret t28 wheels in them and at 17psi let me tell you it pulls hard :P. I do have all the supporting upgrades as well though so that does help. I start spooling at just over 3.5k, at 4k your boosting pretty hard. Give turbonetics a call, I think it cost just a bit over 1g to have your stock turbos rebuilt to be just like sport 500s for not much cashola....