cannot make over 10 psi of boost

[camcojb]

well, one by one I've handled the little issues of a new car and I'm pretty much down to the final one or two on my list. Since I finished the car it will not make over 9.5-10 psi of boost, in any gear up to 6200 rpm or so.

Here's what I have:

402 LS2 turbo-specific build, ET Performance 245cc heads, PMC sheetmetal intake, Nelson Racing headers, twin T67-76RE Precision ball-bearing turbos with twin 44mm Tial wastegates and single 50mm Tial blow-off valve. The 3.5" in/out intercooler was in the car when I bought it and the old motor could run 15+ psi of boost without issue. I have 3" mandrel bent downpipes and full 3" mandrel-bent exhaust out to the rear of the car.

The wastegates started with 13 pound springs and I run a manual boost controller on top of that. I swapped to 19# springs in the gates and tried with and without the boost controller, no change. I added a boost line to the top of the wastegates directly off the turbos, no change. I shimmed the blowoff so it cannot open, no change. I removed the air filters and then the inlet tubes (3" mandrel-bent) and no change. I pulled the inlet/outlet tubing out of the intercooler to see if there was a rag inside or something stupid, nothing. I swapped from the W2W turbo roller custom cam back to the stock LS2 Z06 camshaft; picked up idle vacuum, but no change in boost.

The turbos have .81 exhaust housings, but spool fine. Even if those were too big once it made boost it should go nuts. My laptop shows 160-165 kpa which matches my boost gauge at 9.5-10 psi, so I believe the boost reading is correct. The car runs great, but I'd really like to be able to make more boost. I am out of ideas at this point. I've spoken with Precision and Tial, no answers.

The boost comes up fine and then it's like it hits a wall and stops at 10 psi; that's why I thought the gates or blowoff were opening, but apparently not (I know the blowoff isn't as it's shimmed shut). The only other thing I can think to do is add a boost gauge off one of the turbos before the intercooler just to see what it shows. Does anyone have any other ideas?

Jody