Hey guys, Im a newbe to this forum, but not to trucks, I have a 2006 Chevrolet Silverado Z71 5.3 H.O, and was cringing at gas prices because I can burn a full tank up in not even a week my computer in the truck is saying AVG. Economy 17.3 MPG but I feel that is crap because I think im actually getting worse. I want to improve my Power as well as my Gas Mileage, What Truck Tunner is the Best for the 5.3 V8 I also just have a Magnaflow cat back! Also input as far as CAI would be great, Anyone have a Tunner? Thanks guys hope to learn alot from this site and meet some of you!