I have an '11 Lariat supercrew 4x4, 6.2, Max Tow with 3.73 LS gears. StainlessWorks Headers, high flow cats, X-Pipe, and duals with chambered mufflers, and a SCT Livewire tuner. Around 46,000 on mine and has been flawless. Although not engine related, I replaced the front rotors in April '13 due to warpage, and the battery this past Feb.. On my trips out to West Virginia I regularly get 18.5-19 mpg running 65 mph.. Mixed mileage, if I stay out of it, and do more highway (55-60mph) than city (35-40mph), I get 14-15.5mpg. Around town short trips (post office, Walgreens, market, etc.) is more like 12-13mpg. Now, if I'm having more fun than usual, well.........11mpg?