[Doug Tatham]

It depends what is causing the noise. I would recommend that you take it to an exhaust shop. If it's your catalytic converter, it's a bit early in the cars life to be having such problems - check your warranty. If it's the O2 analyzer you should be getting a check engine light as well. I can't imagine what else could be a source of material that could be rattling around in the exhaust between the manifold and your muffler.