Restricted vacuum hoses at the waste gate solenoids. I replaced all my vacuum hoses and later found out that the stock hose has a restrictor in it. If I'm wrong someone can chime in. Greg also told me that boost increase is seen with these upgrades but check him on weather u need a tune asap or no. I think it be ok once u are not driving aggressively.
"torque gets you off the line...& hp gets you over the line." - TTKeeper