The sound could be alternator or water pump or power steering or AC or any of the idler pulleys........
Pull the belts off and see what happens.
How's the cat? It could be the restriction.
Yeah....I eliminated those. I think the sound is deeper... A thump like one of the rods on the crankshaft?
Yeah... the cat could be plugged. I'd have to fab a "test pipe".
Thanks for the input.