I am in the process of doing the same. With all the mods I have I am only creating full 8lbs of boost at around 4-4.5k rpm. Its like you hit the gas and it is building power and around 3k rpm it starts to create boost then at 4-4.5k rpms it just is beastly. I will bet you are leaking at the intercoolers, and probably just a few various small leaks.