Every time I pull off the track my exhaust has a rattling noise coming from the muffler. It usually goes away after a few days of normal driving, so it didnt really bother me, except this last time it didnt go away. I went to a muffler shop and removed the resonated tips (I thought they were rattling) and when I revved the engine to blow out some of the crap that was in the tips, out came 5-10 small (1/4" - 1/2") size peices of my Catalytic converter. Do any of you have this sort of problem? Is this a sign of my car not running right? What kind of solution is there for this problem? I am assuming that if I continue like this I will need 2 expensive cats come emissions time in a year or so.