aFe Power Diesel Cat-Back Exhaust System for GMC Sierra 2500 HD Duramax 2001 - 2005

The new Large Bore-HD exhaust is engineered to perform in the most extreme environments. This system is constructed from mandrel bent 4" stainless steel tubing for maximum flow, increased horsepower, increased torque and lower EGT's. This system is available in 4" cat-back with muffler. Large Bore-HD exhaust systems are the perfect combination of performance, fit and value.Installation is a Snap:All systems use factory mounting locations providing stability and hassle-free installation.Leak-Free Seal:High quality OE style band clamps are used for a complete 360 degree sealing surface.Aggressive Sound:A free-flowing 24" long muffler is used to absorb high pitch tones producing a powerful sound and unleashing all available horsepower and torque out of your rig.Perfect Fit:OE style bayonet hangers are used to maintain a stable pipe location during high vibration and high heat conditions. The Bayonet tip holds the hanger bushing in place for an OE style fit that does not change with time.Flow and Performance:Large Bore-HD exhaust systems are constructed of 4" mandrel bent stainless steel tubing for maximum flow. Smooth transition bends allow for low turbulence, increasing horsepower, torque and lowering EGT's.Emissions Disclaimer: This product does not require a CARB EO# All aFe exhaust systems are engineered and manufactured in our Corona, California facility.