See if you can find someone local to you that can pull a learning view. That will initially tell you a few things. it will let you know if the ecu has reduced boost to wg pressure because of knock and lowered iam or if you have a gross post turbo leak causing the lack of boost. Otger than that just check everywhere for leaks but it sounds like wg pressure to me as well.
Stage 1,2 & 3 E-Tuning Click Here For Details