Roush 421127 2011-2014 GT V8 Mustang Exhaust With Round Tips Fits 2011-2014 Mustang GT 5.0L V8 and 2011-2012 GT500 5.4L V8 Upgraded aggressive sound tone and volume Provides higher air flow and less back pressure for increased horsepower and torque 409 stainless steel pipes and mufflers; 309 stainless steel exhaust tips with chrome flashing Does not negatively affect emissions