Recently replaced my TD04 turbo with another TD04 (used from a tuner shop 0 shaft play unknown miles) due to it failing ( very loud whine when boosting not normal spool sound ) I replaced the turbo my self, I now notice I am only boosting about 50% of what I should be.. Unless after replacing my boost gauge is off.. It definitely feels slower I don't get that throw back into the seat feeling.. I was wondering did I need to get a tune after replacing? Or possible air leak? I will be pulling it apart Monday on my day off to check all the hoses/clamps and Y pipe for cracks.. I just wanted to get a definite answer to the tune question.
The car is stock except for a cat back exhaust.