Kit Includes The Following: The American Thunder Exhaust Kit includes 16 gauge, 2.5" mandrel-bent tubing to improve overall flow over the stock. The tubing and muffler are made of aluminized steel and comes in a black finish. The muffler ends in a large, 3.5" polished stainless steel tip. The enhances exhaust outflow over stock and offers excellent sound and performance gains. Flowmaster includes all necessary installation hardware and instructions.