Recently started hearing what I would describe as a "raspy" and loud sound coming from the passenger side of the engine on acceleration. It only happens at lower RPMs while heavily accelerating, but all of a sudden goes quiet once above 2k ish rpms. Does not occur at slow acceleration. Any ideas on what this might be?

ETA: 2010 Mini non-S, automatic transmission.

 

Year and model would help. But a guess? Flex-pipe broken.

 

Missed that bit of info in the first post. Edited to show now.