K&N Performance Cold Air Intake Kit 63-3087 with Lifetime Filter for GMC Sierra, Chevrolet Silverado 6.6L V8 Duramax Diesel Guaranteed horsepower gain Designed to improve throttle response and engine sound Free-flowing polyethylene intake tube Replaces entire factory air intake system Not legal for highway use in states adopting California emission regulations This item is not for sale in the state of California/Non-CARB compliant Guaranteed horsepower gain Designed to improve throttle response and engine sound Free-flowing polyethylene intake tube Replaces entire factory air intake system