i have very similar mods and i was getting 8 and 10 psi before i grounded the standard boost solenoid last week (glad i did )
i had a look at my ecu and googled the code on it and the info i found said that it had a mines re-map before it was imported, so may pay to check that and see!?
not too sure exactly what else was changed with the re-map but boost was definitely one thing.