American Thunder exhaust systems deliver the aggressive sounds you want, as well as the performance gains you demand. This T409 stainless steel American Thunder Axle-back for the 2013 to 2014 Mustang GT features specially modified Super 44 series mufflers with polished 4.00 in. stainless tips and is a direct bolt on for the restyled Mustang. A lifetime limited warranty provides assurance that this American made exhaust will deliver that famous Flowmaster sound for many years to come.