K&N Performance Cold Air Intake Kit 57-3021-1 with Lifetime Filter for 1999-2004 Chevrolet Silverado, GMC Sierra 4.8L/6.4L V8 Estimated horsepower gain of 9.12 HP at 5352 RPM Designed to improve throttle response and engine sound Lasts up to 100,000 miles before service is required (depending on driving conditions) Replaces entire factory air intake system Easy to install, usually in 90 minutes or less