that is also over 350 hp mark so obviously it would be restrictive at that point.....Lets put it this way the Record 10 second 1/4 mile, Intense Racing, Turbo GTP runs with the cat back disconnected.
This thing sounds like a jet.
YouTube - 10 Sec Turbo Grand Prix GTP
You need more than a dropped catback and a tune to get away with a 3.4".
I bet your knocking like crazy.
you scanned it and it has no knock at all?(KR)Thats funny! It has no knocks at all!!!!
you scanned it and it has no knock at all?(KR)
you will have max knock at high rpms just before you shift usually....that is where your boost will be the highest, so that is where knock is the most prevelent