So the best bet is to raise the car up and see if I can find any loose bolts and such. It only happens when heat gets to it, or after its been on for 10 minutes.

Yeah, your best bet would be to get under the car, follow the exhaust, and check for any excessive movements.

Ya gotta remember, heat weakens metal, so something that seems nice and tight when cool may be a touch looser when hot (Yeah, I know, metal expands when hot, but it also gets softer).

I would not recommend getting under the car while it is running. Not even with jack stands. If you feel you trust the stands, and that you need too, do not do this alone. Have someone there, just in case something goes wrong.

Yea, I got ramps and a few jacks I put under my car, but since I got the new tires, it is a really tight fit and I dont like to do it. I will usually go up to the craft shop and drive it on a ramp then raise the whole car 7 feet in the air. Going to do that pretty soon anyways to change the oil. The noise is just annoying neusance

Sounds to me like the new exhaust has internal sheet metal parts that "loosen up and vibrate" when they heat up. A friend of mine had this happen to a Chevy, and the shop that put the exhaust on finall replace the muffler with a better quality one, problem was solved.

Muffler is from jegs, but I think it is around the cat that is giving me problems.

my car did that and it was the exhaust shield above the muffler came apart from the the body and was just laying on the muffler causing this gawd aweful racket that i couldnt find anywhere until i got under there and started shaking things about and found it and the one for the cat was loose and hanging down also!!! Just something else you might want to check!!!

Thanks, I forgot about the heat shields.