I had a jet sounded turbo on my last one turned out id killed it through to much boost (needless to say ill not take it to that tuner EVER again)

My guess is that the Act is poor, or the bottom turbo hose tends to colapse under load restricting air flow, they also split after time so check that its not pulling air in anywhere.
Dump the dump valve because i dont care how good they are they can lead to so many probs that point else where.