I seem to be lacking some boost on my wifes 2004 1.8t Avant Itâs kinda weird as although I think it is down on power its still not slow. There are no fault codes and no leaks as I had a smoke test done on the system. My thoughts were a N75 or Diverter Valve. Both are stock units atm and the car runs stock. I donât have access to boost gauge so unsure what psi it is running. Couple of questions: Would a fault in one of this cause a fault code? If I replace the N75 , which part number do I need? Any other suggestions would be appreciated as to the issue.