These Supplemental Fuel Pump kits are required for GM trucks utilizing #1577, #1578 and #1579 E-Force Supercharger systems. Failure to use the supplemental fuel pump kit may result in engine damage. These supplemental fuel pump kits are not required for Flex Fuel models. Flex Fuel models come standard with adequate fuel systems that properly operate with the Edelbrock E-Force Supercharger system. These supplemental fuel pump kits include a replacement fuel pump, control module and fuel level sender (system #15791 also includes injectors).