i just got this 97 a4 1.8t and its my first boosted vehicle so i am pretty new to it. bare with me here but the guy i got it from said it was pushing 15lbs of boost. . when i drove it it would only get up to about 5 1/2 at 6k rpms. it has an aftermarket bov but im not sure what kind.. could someone help me out with why it isnt building alot of boost?

 

It is most likely in limp mode. You will need an eBay vag com cable and VCDS Lite to scan for codes to figure out where the problem is.