I do remember Randy or Ken from Mountune say that if you have any other improvements ie aftermarket exhaust etc that because of the increased power and torque the ecu will hit an allowed torque limit thus limiting boost to a slightly lower value. Not too sure if CSM has any other mods to his which could cause this. Other than that the only thing I could see as Tokendog said enviroment, altitude and possibility a loose fitting somewhere.Yeah, I'm no expert at this by any means but I am under the impression all kinds of things can impact your turbo's ability to make power. Environment, altitude, etc. so hopefully someone can chime in and give you some insight or things to look for.