joseph mitro

i have a bad rattling right about 3000 rpm. annoys the heck out of me. i hollowed out the cat, but the body is still there. i'm thinking it's either the heatshield above the cat that's loose or something in the cat itself.

any other thoughts?

Serge944

Balance shafts? When mine were misaligned, i got vibration at 3k.

Chris_924s

Mine had a rattle at 2900 and 3200. It was misaligned exhaust hangers. Bugged the bejeezus outta me.

Carl Nall

Was the "rattle" present before hollowing the cat? Possibly the "rattling" sound is a resonant frequency of the motor freed from the muffling effect of the stock cat, i.e., unpleasant engine firing noise exiting through the exhaust. A similar noise is produced when using header and test pipe although it seems to be evident at part throttle throughout the rpm range. I avoid the rattle by keeping the throttle fully open when at all possible. YMMV.

Serge944

Good point! I had a resonance when I built my test pipe. I then got rid of it (you know that joseph, dont you?)

Chris_924s

Excellent answer.

joseph mitro

nope, not balance shafts. yea, i know about your test pipe. i'm thinking i need to get rid of this hollow cat and either put on a straight pipe or maybe a high flow cat.

and yes, i do like the WOT concept