I'm not sure this is what you are looking for but I bought Corsa Sport Axleback GT500 Quad Exhaust from AM. Love them. My husband put them on his 2014 GT/CS also. Not sure these are the size you are looking for or not. You can check them out.
---------- Post added at 02:39 PM ---------- Previous post was at 02:39 PM ----------
Not selling just suggesting where you can buy them.
2 2014 Mustang GT/CS Premium California Special Race Red 1 Convertible Black Top
1 Coupe with Panoramic Roof and Navigation System
Vert Pioneer's 8100NEX and back-up camera
Both Vert and Coupe 6 speed Corsa Sport Axleback GT500 Quad Exhaust, comfort package