I didn't check all of the exhaust manifold bolts but the few that I did check were solid. I could not find any cracks either. There is a leak on the right side, where the four pipes connect into one. I plan on having that fixed soon, so that will help with the noise issue.
I know its hard to say what the problem is, esp not hearing it yourself, Mike. I appreciate the help. Sorry to have hijacked the thread Dominiq.