I have a friend with a '93.5 TT automatic. He went out and bought an Apex cat-back exhaust from Ebay that was used. Anyways, he got it put on by an exhaust company and everything was working fine for the first couple of hours. After that he was on his way back to town and when he steps on the gas it kinda lags. He came over to my house and I rode in it and everytime he gets down on the gas it really lags and it doesn't accelerate very fast. The only way he can get up to speed is by barely stepping on the gas pedal and let it slowely accelerate and by doing this he can get up to 95 mph and so on but same problem happens when he gases it all the way. I told him it might be boost cut , but I thought that boost cut kicks in at a high rpm? The only mods he have are a downpipe and the Apex cat-back. Anybody got any ideas on whats going on?