Just returned from Atlanta, GA after getting a BB tune-up from Justin. I got 18.75mpg from Jackson, MS to Atlanta. After tune-up, Atlanta to Jackson=21.25. Very impressive for a 2003 Tahoe 5.3L with Gibson Dual Sport Exhaust System, AEM CAI, Granatelli MPG wires, E3 plugs. Also, Michelin LTX...