just installed mbrp, now im having probs

[1BAD99]

ok guys, I just got home from installing my 4in turbo back exhaust, and she was running great and sounded awesome. well on the way home after i was driving for about 30 mins, I went to pass a car under light load and the truck acted like it was hesitating. It now seems like the truck doesn't want to boost and acts laggy if I try and give it too much throttle. its now dark out and I cant really work on the truck at the moment but plan on taking a crack at it first light. any ideas as to what it could possibly be? my truck is a early 99 f350, gauges, leveling kit and mbrp 4in turbo back. thanks for all your help. also one more question. my truck was seeing 14-15psi at full throttle. is that normal boost?

[1BAD99]

the only things I was thinking it could be at the moment is that I either somehow didn't tighten the DP enough which I think is unlikely, the turbo blew although im not blowing a bunch of smoke, or if I blew a line off.