my dad recently bought a new avalanche with the 8.1 and 4.10's. He's pretty light on the pedal and only squeezing 11.1mpg out of it. Do you guys think a drop in K&N filter would make a noticeable difference in mpg? He's not real big on modification. So anything more than this is out of the question.

 

I think the k&n would improve the mileage. An engine that big isnt like the 48 or 53. You can put a cold air on one of those and not really tell too much bc they aint suckin as much air. I believe on an 8.1 it would have a very noticeable increase, as long as you keep your foot out of it!

Derek

 

I know for a fact that a CAI will help gas mileage on the 8.1L. I have a 2002 RCLB, and it picked up 2 mpg. My uncle also owns a GMC EXCLB and tows with his. Without a trailer on he gets around 13-15 mpg. He's light footed too. Myself loved the throttle repsonse. Huge difference there. Is it worth the money? Eh maybe. I would shop ebay for one....