The material inside of the cat comes apart in chunks and tends to rattle around. Put the car on jacks or ramps and try to shake the exaust system (careful! it's hot!) If something is loose inside, you'll hear it. Someone once told me that he took his cat off, knocked all of the stuff out of it and put it back on. He took it down for emisions (twice now) and it passed with flying colors! I don't remeber who it was that told me that, it is illeagle to modify cats like that. I thought it was interesting though. You may simply have a loose clamp on the exaust. I have seen that before. Good luck
Last edited by milehieagle; 06-18-2003 at 12:22 AM.