for the past few weeks i have been hearing what i thought was a loose muffler mount from under my 97 tj. thought it was that or the baffles in muffler were just wore out. took it to local guy who always does excellent work at his muffler shop and to my dismay he advised me that the "rattle" was my catalytic converter. i always keep my cargo hitch carrier mounted to jeep and of course it rattles a good bit. didn't want y'all to think i had mistreated family toy. i guess this somewhat threw me off, but going to only use cargo carrier when needed. hope this improves gas mileage a little and was lucky didn't have any damage to heads. put new cc on right there on spot was afraid to drive home.