I have a similar problem with only 3 psi, and was because a leak from a coupler, but ok, i fixed and i checked all couplers and clamps, and now only have 5 psi, even using my MBC to go higher, boost are still at 5 psi.

 

Sounds like a fucked actuator ..so the flapper doesn't close as it should.
Double check all charge pipes and clamps , you're boost is eluding you!!

 

My MBC can only leak .3 on the dyno more and .5 more on the open road

 

not much of a controller you got there is it?