I noticed this weekend that my 08 GT has a sound coming from the rear of the car...it sounds like something flapping/tapping back and forth...It only happens when the engine is under load...it doesn't seem to happen when you hit a bump...only when you are accelerating...and it doesn't sound metallic...I checked exhaust, everything I could get my hands on...haven't found it yet...anybody had this???? I noticed that the rear bumper is pretty flimsy/floppy in the middle at the bottom...could the added vibration from the Pypes exhaust be vibrating the bumper??? I am stumped on this one...any ideas???

 

I guess the obvious question is "did it do it before the pypes exhaust went on" ?