Ok my funny noise is a muffled vibration/clattering whenever I go over a bump. It is coming from the rear left. Thought it might be the exhaust (which is rear left on a 2.1) come loose but when I crawled under I found the exhaust is intentionally loose since it is suspended by rubber hoops its entire length. I can see the whole exhaust assembly swings freely so I think the frequency of the vibration I can hear cannot be the exhaust since it is too quick. Any other ideas?

Car has recently been roadworthied so I don't think it is worn shocks or loose suspension components.

 

Check your rear sway bar/bushings/bracket. They have a nasty habit of breaking.