That is My kit that you are talking about that is being used on the stealths/3000gt's, we sell it for $525, it allows stealths/3000gt's to run about 7psi more boost on 91 pump gas (22psi vs 15psi)...
here is a vid of A person that works for me, driving his 3000Gt VR-4, with up-graded turbos...