Just repaired same problem on my S-500 coupe last week. Mine sounded as if the tail pipe was hitting the body. Turned out to be the front swaybar link. Cost me about 40 bucks for piece. A little work to replace. Had to remove caliper and disk to get at top mounting bolt on link.Be sure to place a jack under sway bar to relieve pressure before removing bolts all the way. It was a crazy kind of set up. You will need to hold an allen wrench while removing bolt you will see not to tough and will made great improvment I will be doing other side and frame bushing when weather brakes here in Jersey. Good luck Voz