A 4" suspension lift and some 33" tires will really make that stand out. I have a buddy that did that to his. Funny thing, That has the same drive train as my avalanches and his is a terrible gas hog compared to mine.
Got 15mpg during the snow-ma-gedden we had last week (4WD was on most of a couple days) but getting 19mpg average travelling from work and down to Dayton, TN taking care of Vickie's mom. I'm happy with that...if I can just keep my foot out of it....it's a hoot to play with. Don't know about lifting it or anything except a flowmaster splitting the single into a dual outlet. Looking forward to hearing it rumble....that mod is down the road a bit.
Amen on the drivetrain....looked up under the truck prior to purchase and everything is heavy duty for a "small" pick-up. Should be a good vehicle for many, many years.