Not sure about the vibrating/noise, but it could be something to do with the wastegate (might be stuck open). Also I'd check all the lines and make sure that there are no leaks (your vacuum/boost gauge should help with this).
Is it running factory computer?? Sometimes if there is a problem with the engine (a sensor down etc) they resort to base mapping & no boost (well 6psi is no boost

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Also, sent you a pm about the stuff you have for sale