So this CPO 2011 we just bought has a funny sound that sounds like something is loose in the under carriage right under the driver's door area. Upon start the engine seems a little louder than it should be which i thought may have been just the difference between the 4.2 and 5.0 but it quiets down after a few seconds but when you go to accelerate or rev the engine you hear that "rattle" which is not coming from the engine compartment but again from what sounds like under the driver's side door. Sound like maybe something in the exaust system is not as tight as it should be?? Its still under the oriignal warranty so I have an appt to dorp it off Friday but just curious to know if anyone else may have had this problem.