Hummer H2 American Thunder Exhaust System. This Flowmaster 50 Series Force II Cat-Back Exhaust System is designed with the latest technology to provide the best possible performance from a Flowmaster muffler. Looking for the famous, full-on "Flowmaster tone?" Look no further. American Thunder will deliver the aggressive tone you want, as well as the performance you demand. Flowmaster's systems will both improve acceleration and passing power, as well as increase fuel mileage. Every system is individually engineered and dyno-tested for each application and includes all required mounting hardware. All tubing is mandrel bent for the best possible exhaust gas flow, and both tubing and mufflers are fabricated from aluminized steel for corrosion resistance. Systems include: Performance Flowmaster muffler(s), all pipes with hangers attached, clamps and mounting hardware, detailed installation instructions.