i just bought a 2006 1500 mega cab with HEMI. Its has what seems to be about a 2 inch lift or leveling kit and 285/70/17 cooper AT tires. Few questions. 1- Will this size tire affect mileage much? I got around 12.5-13 mpg on way home and getting around 10.5 now just putting back roads. I understand its a larger motor and wont get the best mileage but [censored]. 2- The exhaust is a head scratcher too, over the rear axle seems to be a smaller muffler Is this normal or a add on from previous owner? The truck is quiet for sure( half as loud as my old 4.7). What are some things I can do to help improve mileage? Oil change, plugs is what Im thinking along with intake clean up. Thanks for any advice or answers.