Originally Posted by Däs Schmoo
Why not just get a larger trim T3/T4 and run less boost?
The restrictions I see in your setup that could pose a problem are the downpipe, exhaust, turbo, and/or manifold.
try doing a couple runs open down pipe, with a .48 your not gonna have an agressive top end, even on a d16 so you should only expect a strong midrange. I dont think your head is the issue, my friend is making 450hp on a stock head, youve got problems else where. The fact that your not getting 10 psi on your 10psi spring leads me to believe youve got a leak somewhere. might be in the manifold, or its the lines or charge pipes and you just havent found it