Cant figure out this knocking noise. I have a 2002 gtp. I have ssac headers, 3 inch downpipe, no cat, no res, stock mufflers, 180* tstat, k&n cai, zzp stage 1 throttle body, dhp 1.0 pcm, 3.4" pulley, fuel pump re wire, alt re wire. I have a knocking noise from 2500 rpms to about 3500 to 4000 rpms. it doesnt do it after 4000 rpms and it doesnt do it before 2500 rpms. it doesnt do it in drive that i can notice. i think its coming from the front of the car but i cant figure out what it is. any ideas on what it is or any suggestions how to fix it? please help