So this sucks really bad! i have a 2006 mustang gt auto with 4.10 gears, stage 2 comp cams, 62MM TB, TCI shifter. bought headers off ebay (dumb idea) they dont fit directly and the driver side header is rubbing the steering shaft. so i got on americanmuscle.com and ordered new bbk long tube headers and a X pipe (without cats). the issue i am talking about now is it sounds like there is a knocking noise coming from the right side of the engine. to me it sounds like deep down in the engine! it is a loud knocking sound when i first start the engine when it idles really high where is the engine is still cold. after the car warms up there is still a knocking noise but it is kinda hard to hear it untill u pop the hood! then u can hear it when u put your ear down close to it but it seems like here lately it has been getting worse. so i stopped driving it. before i quit driving it, it seemed really slugish, when i would try to pull out it would almost act as if it had a miss, and even after it was warmed up when i would stop at a light it would idle low possable around 500 RPMS. what really confuses me is it does not have a CEL. i wwould figure that it would pop a knock sense code but nothing yet. my vehicle is really loud so it makes it hard to hear alot that does on with the engine (since i have no cats) but the knock is still loud enough that i can hear it. what could be the possable causes of this? cranck, head, piston, cam, what? my uncle owns a garage and he is a licensed machanic and he will be doing the work for me and i will be helping. but i would like to know what the possable causes is before i get started. any adivce will help thank you!