Got a nasty noise!! I hate metal noises...'00 SSei is making a pretty bad rattling noise when I start it until it warms up a bit then you can still hear it when you excellerate. It sound like it is coming from the exhaust but it doesn't necessaarily sound like it is a manifold issue. My first car had a similar noise and is was the lining of the muffler that came loose...is this a possibility here?? Thanks for any input!

Mac

Moving to 2000-2005.

Could be deposits in your cat making the noise?
How many miles on your car? Do you burn premium fuel?

I agree with PDad. Likely the cat. Give it a good kick and see if it rattles when you do that.

No I do not burn premium?? Should I? It has approx 94,000 miles. Is there something I can do to clean it out to help diagnose the problem? Thanks for any help!

Mac

The chunks are most likely carbon deposits that can effect the performance of your cat and exhaust system.
I dont have any recomendation but to change the cat if your sure the rattling is coming from there.
Not sure if sea foam would clean a cat?
Running too rich or poor fuel can cause carbon build up, a good tune up including injector cleaner will help.

Yes...the supercharged engines require premuim fuel...you will find you get better performance and gas mileage with premium...even though it costs more to fill up, you will go more miles - the cost is the same or less in the long run.

the fuel cost works out to be rougly the same, and the premium fuel will help preven knock, making your engine internals run for longer