[jeffcoslacker]

PS I know you've probably already thought about it, but exhaust shields account for the major share of odd metallic buzzing sounds that only occur in certain rpm ranges under certain loading...

And Accords have a buttload of shielding....

Take a hammer and smack each one lightly, working from the one around the exhaust manifold down and back all the way past the cat covertor...one that has a broken weld and is the culprit will usually sound odd, a little dead and buzzy whereas the intact ones will kind of ring when struck.

If you find a bad one, usually one or more welds that hold the halves together have broken....you can have them welded, or get an oversize screw type hose clamp from the parts store and crank one down around it, that stops the noise too.

Make sure the exhaust hangers under there aren't broken or the hooks haven't gotten bent somehow...this will let the pipe push sideways and can make contact with the heat shielding in the floorpan tunnel, etc...