Just had GT500 mufflers put on my car today by the local Ford dealer. First you can hear the stock 2013 Mustang GT mufflers at idle and drive-bys and then the GT500 mufflers. The GT500 mufflers here are brand new and will get louder after 500-600 miles as the packing ages. Too bad but it was windy when I shot the GT500 sounds so that diluted the sound somewhat. But you should hear that the GT500s are louder than stock but not as loud as Roush.
Joe C 2013 Mustang GT with stock and then GT500 mufflers - YouTube
Music to my ears! Best sounding exhaust on this car, but I might be biased:laughlitt I think the best improvement to the GT500s would be longtubes!
2016 gt premium, ingot silver, performance package, navigation
2012 gt premium, brembos, 3.73, 6mt, kona blue
2015 Ecoboost PP black on black 401A, security, enhanced backup