I put a Borla catback exhaust on my '07 GT when it had 1500mi. on it. On occaision, when I've driven the car for say 20 min on the highway at between 80-95mph I notice that when I get back into town their is a rattling sound coming from the mufflers when I accelerate from stops or just mash the gas pedal a little harder than I wouldneed togoing from stop to stop. When I put the car in neutral the noise stillcomes from the mufflers, sort of like there's a loose golf ball rolling around in them. When I pull over and check, the pipes are tightly fitted into place but last night I also noticed a strange electrical burning type of an odor coming from the tail pipes as well. The car itself was running at the correct temp and the oil level is still perfect ( at 46OO miles now, third oil change Mobil 1 5w20)and though the engine compartment was on the hot side itself, there was no strange burning odors coming from it. After letting the car cool down 12hrs while I was at work it sounded fine all the way home on the toll road (speeds up to 105mph for short periods and 80-85 for most of the ride) and no rattling when back into town. I'm concerned there's some problem with the ceramic baffles or whatever with these mufflers but I thought I'd post here first to see if anyone else has had this type of thing with aftermarket exhaust. Thanks for any and all help!
Rick S.

 

Make sure the exhaust hangers aren't near the rear bumper. Sometimes on the driver's side it looks like there is enough room but when you start driving, it will hit the bumper and cause a sound like that. Also check to make sure your over axle pipe has enough clearance and you aren't hitting there.

 

Thanks, will check the hanger and the clearance. I did a search here after I posted and found some more posts about exhaust rattles so at least I know I'm not alone. I was worried sick that the Borlas were bad and that I'd thrown $800 down the drain getting them. They really made this Stang come alive sound wise and as the car breaks in it just gets better and better sounding and performing.