I have been hearing a loud rattle under my truck since a trip down to Attica in June. It sounds like someone stuck a Cummins in there. Apparantly somebody snuck into my driveway at night and bashed my catalytic converter with a rock. The media inside is broken up and rattling. Time to replace them with catco cats that will fit better with the sliders. The same vandal also bent the snot out of my exhuast. While it still passes gas OK and doesn't leak, it rattles. Might be time to find a better route that doesn't require so many passes under the frame. A big part of me says fix it with parts that work the way I want them to work. Another part says that Toyota's are the best made trucks out there and the exhaust has been no exception. 115K miles and it's in great shape other than damage caused by abuse.