Do you still have the STI TMIC on there? I've never used one on this size of turbo, but it seems to me that could be restricting you some. A 3076 at 22 psi is a lot of air to flow through there.
You should have your gauge reading manifold pressure, not boost pressure after the turbo.
With your setup, with no leaks and a solid BPV, the way I see it, there is either a restriction somewhere or the wastegate sping isn't enough.