I have a k&n in my 06 express 4.8 gave me .5 - .75 pg increase without question...slowing down is the cheapest and easiest..looking into a bully dog tuner...heard that can get you 2 mpg...
I just turned 500,000 on my van...@ an avg of 17 mpg that's 30,000 gallons of gas....if I could have avg...