ORIGINAL: sailors06GT

I had the same problem with my 06 GT and took it to my dealer. I also thought it was a heat shield. They took it for a road test and confirmed the noise. Then they tightened the exhaust hangers. I took it home that night and it was still making the noise. So, I took it back and went on a road test with the guy myself and showed it to him again. They took it in the shop and revved the engine hard several times and got it to make the noise sitting still. After about an hour or so the service manager came and got me and told me it had to do with some gap or somthing with the bolts for the inspection cover on the bell housing and that initially with the new body style mustangs(05+) Ford left out a couple bolts on the bottom (the only two that are visible), but mine were all there and they put some RTV around the bolts. THAT SOLVED THE PROBLEM, at least in my case. So I would go back to the dealer and ask them to check out the bolts around the bell housing. See if that takes care of the problem. I think it should. It sounds like the exact same problem I was having. Good luck to all of you and hopefully this helps. I know it sounds a little weird, but that is what happened to mine. Even if you don't have it fixed, it is not something that is going to be a problem, at least that is how it was told to me. Good luck again.