Yes it improves Mileage and Horsepower.
Reviewed By Roy A (JACKSON, TN) Reviewed for a 2007 GMC Yukon —10/9/2014 2:40 AM
I installed the K&N on my 2007 Yukon Denali with the 6.2. City MPG increased 2.2 MPG and Highway improved 3.6 MPG. I also changed out the plug wires and plugs so the result is from a combination of all three but yes it does work.