The Edelbrock E-Force Supercharger Stage 1 Street system part # 15770 for 2003-06 Silverado and Sierra 1500 and 2007 Sierra Classic increases the performance of your 6.0L Gen III engine to 364 horsepower and 397 ft/lbs. of torque at the rear wheels, when used with Edelbrock tune (kit supplied without a programmer). The Edelbrock #15770 Supercharger also works with the 4.8L & 5.3L Gen III engines, HP & Torque numbers will vary. The core of this system is the Eaton Gen VI 2300 TVS Supercharger rotating assembly with a four lobe design with 160 degrees of twist for maximum flow, minimum temperature rise and quiet operation for excellent drivability. We also designed our superchargers with an integrated bypass valve to help eliminate parasitic loss under light throttle, improving mileage potential. Our unique and efficient inlet configuration results in a shorter, less restrictive intake path for improved air flow, without the need for a jack-shaft. Keeping the air cool is a high capacity air to water intercooler and low temp heat exchanger. HANDHELD PROGRAMMER NOT INCLUDED. Supercharger systems sold without tuners are only emissions legal when used with the correct Edelbrock program, which can be downloaded at www.edelbrock.com. For safety, the Edelbrock supplied program will retain the factory vehicle speed limiter setting. The #15770 system increases the performance of your 4.8L Gen III engine to 339 horsepower and 359 ft/lbs. of torque and for the 5.3L Gen III engine increases to 339 horsepower and 359 ft/lbs. of torque at the rear wheels, when used with Edelbrock tune (kit supplied without a programmer).