Gas milage help!!!

[adamw89_2000]

Ok, I know I didn't buy my hummer for fuel milage but I'm averaging 7.5 by my dic panel! Yea and I'm pretty sure it's accurate as much time as I spend at the pump... It's an 05 sut lifted 8" with 40" mud Trappists and 20x12 fuel rims. The tires are 15" wide as well. I have the cats removed which is throwing a code at the moment and I have stock gearing in it.... Is there anything I can do to this thing to get better than I am now? I'm starting to drive more and if I pussy foot it and go very slow I get almost 9... This is all in town milage for the most part. Any suggestions?