Reviewed By David V (Kennewick, WA) Reviewed for a 2007 GMC Sierra —1/30/2017 10:22 PM
After installing this K&N Cold Air Intake (which was exceptionally easy) my Duramax started purring like a kitten. The idle just smoothed out. I haven't checked the mileage yet, but I'm sure it has been positively affected. I wouldn't buy any other brand.