Next, i'd look into shimming your wastegate to hold 8 psi with some thin washers.
You must have done something wrong. Maybe too weak a spring in the controller or the ball is out of round or maybe your ball seat is out of round. Did you check it before installing it?
Goodnight sweetheart...yes its time to go...bum bum bum bum bum...good night sweetheart yes I am one little a$$hole......bum bum bum bum....
