i have a 2007 harley f150 awd( no sc) i put a k&n cai on and it ran great no knocks and more power. heard they can run lean without tune and i wanted more power so i got an x3 from vmp. on my 93 performance tune it was knocking at higher rpm 4000 + .justin said to take a few degrees of advance off and i did. it seemed to solve but i believe i could still hear intermittent below 4000. so i dropped more advance off in lower rpm i think it help but afraid off running lean and hurting engine. I was told by sct that a knock could not be to much advance but to lean as the cause. so taking advance out wont really help. and also when in first gear and second from down shift it bounces up and down slightly at higher rpm at WOT and in second it hits 3000 and drpos 200 rpm then back up at WOT????