If you do not know already, Duramax trucks do not come with any lift pump supplying fuel to the injection pump. This added stress on the fuel system can create poor mileage and low power especially under a loaded situation. The factory CP4 injection pumps are substantially weaker than that of the previous model years CP3. Not having a steady reliable flow of fuel will increase the risk of the CP4 failing. Adding this pump from Fleece will drastically reduce the chance of CP4 failure. Also, any time a tuner is added to these trucks, more fuel is demanded out of the injection pump and if there is no fuel supplying that pump, you are loosing power! Adding a lift pump system to your LML will help improve overall efficiency and mileage. They are however absolutely necessary for anyone that wants to make power on these trucks. Until now, the only options were frame mounted pumps that look out of place on your LML Duramax. No more noisy lift pumps, cutting holes in your fuel tank, or quarter tank issues. Fleece's drop-in lift pump allows for silent operation, utilizes the factory connections for an easy installation and its active fill bucket technology eliminates the need for a draw straw or tank sump. The PowerFlo Lift Pump operates with two OEM quality gerotor pumps that have surpassed 12,000 hours of durability testing and together flow 170 GPH @ 15 psi, making the PowerFlo Lift Pump capable of supporting 800+ RWHP.