I have an '05 Sierra 2500HD with the 496 Gas motor. Looking for a good tuner that also allows changes for larger tires and can help with MPG. Seeing as though I only get about 9mpg. I like the Hypertech Max Energy one, but let me know if you guys have any thoughts or something for sale that may work for me. Really just looking to correct my speedo as I have 20" rims..Thanks,Chris