Flowmaster's American Thunder downpipe back exhaust system for the 2001-2007 Chevrolet and GMC 2500HD and 3500HD pickup truck is perfect for the person looking for a moderate sound level with all of the performance benefits that you would expect from Flowmaster. This DOS (Dual Out Side) bolt on system for the 6.6L Duramax diesel engine features a special Power Chamber muffler, dual 4.00 in. 409S stainless steel tailpipes and 5.00 in. polished stainless steel tips. This system is designed to fit all wheelbases, except for Standard Cab/Long Bed models. The exhaust system is manufactured in the USA and is covered by Flowmaster's Lifetime Limited Warranty. Designed for an easy fit, this system includes all necessary parts and hardware for installation.