From what I understand , they all have KR from the factory.. Mine has 2-4* KR , usually during shifts.. Could be false knock as well, but I like to look at the worst case scenario.. Headers, rockers, or a IC would be a good start, or get on a dyno for a full HPTuner setup.. If you pick one of the bigger 3 mods I just mentioned you should have zero knock on stock pulley, From what I see alot of guys withh older GTPs run a 3.4 on headers, rockers, Tune, 180 stat, 605s.. sell the DP if you can and look at speed Daddy headers, as they seem to be the best bang for the buck.. Im actually debating on picking up a pair myself, as they are pretty descent , being a SLP knockoff.