Quote Originally Posted by zamoramax View Post
Sorry early '06. It only does it under load. Wouldn't say tiny, almost like a heat shield that's loose but I can't find one. I was able to duplicate the noise by roughly shoving the exhaust. Seemed like it was a seam before the cat but just after the turbo. Tried loosening the clamp on the seam and tightening but no luck... plus it didn't want to pop off...

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With the truck cold, try to beat on the catalytic converters with you hand and see if it rattles. I'm thinking the core may be lose. If you hear a slight clunk, that's probably it. Unless it is something you can't live with, you can leave it for a while. If it get's worse in time, then replace it. Not sure what your muffler design is, but it could eventually partially clog it. If it were a gasser, I would say get it out as there are 2 converters. 04 and newer cats were mandatory. Heavy fines if your caught without it. There's a slim chance of that happening unless you like to smoke.