The FLO 728 is a 4" DPF Back Dual Exhaust system for the 2007.5-2010 Duramax 6.6L. It replaces your restrictive OE exhaust system from the DPF back with a 4" mandrel-bent dual exhaust system, this kit does not include a muffler and is designed for race applications. Just like all of Flo-Pro's Exhaust kits, it will come with all the required clamps, pre-weld contour bent hangers, and stronger flanges to help you cruise through the installation process. This exhaust not only sounds great, but will improve your torque, mileage, and throttle response!