I installed the ReadyLift 2 1/4" kit into my front end. It's a 1 1/2" spacer on the top and a 3/4" spacer on the bottom. Brought it up but just under level. Perfect! It rides the same and no noticeable MPG change.
http://www.readylift.com/products/gmc/gmc-sierra-1500/leveling-kits/gmc-sierra-1500-2007-2013-2wd-4wd-6-lug-2-25/chevy-silverado-1500-2007-2013-2wd-4wd-6-lug.html