yes you heard right… i just picked up a 94 accord lx… and the exhaust buzzes from like 2000rpms-2500rpms, its sounds like its hitting the frame or something, but nothing is loose, or such… also after that when above 4000rpms, its rattles, like a heat shield is loose, but underneath, nothing on the exhaust is loose or such…i dunno… lastly when i turn my car off after returning home from work… my exhaust clicks like every 10 seconds, and then as the car cools down, the clicks go down to about 15-20 seconds intervals… i can hear it, when i lean under the car… but what the heck is this noise, im almost positive… thanx in advacne… any help would be coool…
kevin
Heatshield?
Edit Read again and I see you eliminated heatshield… Dont know then
i didnt eliminate it, just through a couple of screws to hold it tight… ive went under there and punded at the exhaust, and dunno what it could be that rattles??? beats me
its probably the catalytic converter…on my focus when i took the stock one off i was having the same sounds…the insides of it were all broken up and rattleing around and bangin each other and stuff
take the cat off, and try to claim it stolen 
Muffler bearing.
Grease your muffler bearings! 
Sorry, had to…
Anyhow, I second the damaged cat if you’re sure there’s nothing else rattling. You may want to double check all the bolts and nuts on the exhaust system, make sure they’re tight even if you can’t feel it rattle.
EDIT:
Dammit, beat me to it!
5 bucks says its where the header meets the exhaust/cat where the spring bolts are. Just get new spring bolts or just get nuts and bolts and bolt the fucker down and I’ll almost guarentee the noise goes away.
buzz / rattle is often caused by a broken spotweld inside the muffler, causing a baffle to move with the exhaust pulses.
sometimes the baffle just hits the housing, sometimes it hits other baffles. this type of noise id RPM dependant
clicking on cool down - usualy caused by any 2 hot pieces of metal that are touching. most often heard at a manifold connection, or around the converter. this type of noise most often is nothing to worry about. its simply caused by a difference in expansion / contraction rates of 2 items that are bolted together
alright… i double check the bolts tommorow…and tighten them, and possibly throw a new cat on it…