At 500 Rwhp that shouldn't really be to much of a issue. Did anyone get a pressure reading before and after the turbo and compare that to the boost reading? That is truly the only way to diagnose whats going on.
All and a rich tune and really retarded timing also will add to the boost creep issue due to burning fuel in the headers, Which will make that thing spool like crazy right now but when the tune is cleaned up that will be gone plus burning fuel in the headers will void the 4 year warranty they...
After looking at the picts I'd say back pressure isnt a issue. Cant see the tails but I assume they are 3 inch.
The kit is a normal plain-jane street kit with a big turbo. In the form it appeared to be in at the beginning even with the crossflow Aftercooler. It would have easy been able to...