I have NOT ruled out exhaust issues...in fact...I found a hole in the weld at the headpipe to flange...I tossed some JB weld in there to give me 5 minutes to see if it would shut the noise up, but it didn't....At first, I was convinced the main noise was coming from the manifold....I am still not sure, but my gut is telling me it sounds more metallic than exhaust leak...