So, I've been noticing a strange noise in the car lately. At first I though it almost sounded like an electronic feedback coming through the speakers. Last night I had the car on a lift checking my exhaust install for leaks and I heard where the sound is coming from. It's an intermittent hissing sound (best way I can describe it) coming from the left and right underbody near the rear wheels. Anyone have any idea what that could be?

 

More than likely an exhaust leak in that location.

 

Definitely not an exhaust leak. I was under the car checking for leaks as I had just installed a new exhaust. The areas the noises are coming from are part of the underbody. They're pretty far from the exhaust. I'm stumped.