Check your exhaust hangers, the rubber donuts that keep the exhaust up, might have broken one or more. Also check the exhaust mount bushings at the transmission.
Collapsed motor mounts can also cause the exhaust system to hang lower and make contact with structural parts, usually manifest with a solid rattle under certain engne speeds.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.