So my boost was falling (12psi down to 8psi) and I was hitting max hp at only 4800rpm. No signs of belt slip. Thought maybe wasn't getting enough air with the stock LS6 throttle body, so I upgraded to the LS2 (90mm). I couldn't find an LS2 snout so I used the adapter plate and just ported out the stock snout to match. Also used the adapter wiring harness. Took it to the tuner and he can't figure it out. It seems to run good up to around 5k and then just falls on its face, I mean completely. He said normal TPS reads 86% at WOT and mine is reading 100% and it's not changing anything in the tune. There are no codes that he mentioned and it's not going into reduced power mode. Could it be a bad adapter wiring harness?? (got it from Summit)