low boost

[btingle85]

Hey guys. Just got an 07 6.0 with 177k miles. It's in great overall shape. I put a 4" exhaust and an airraid cai after getting it. I don't know if it has anything to do with it but I was peaking at around 18-20lbs before exhaust and now it peaks at around 11lbs. I have cleaned the egr valve. Replaced both fuel filters. Found a crack in the blue boot on the intercooler pipe on the turbo side, replaced it. No difference after these checks/changes.
What else would cause this low boost and hesitation at wot? Anything else I could try/check? Thanks in advance!

[Lilpooh]

Check for soot at the flex joints on the up-pipe and y-pipe. Sounds like you have an exhaust leak between the exhaust manifolds and turbo, the flex joints tend to crack/fail.

[btingle85]

Thanks lilpooh, I checked the up-pipe and y-pipe, both in tack. It turns out it was the map sensor tube, had a tear in it. Replaced it along with the map sensor itself and it is running like a top again.