so basically you went .5 better due to losing 500 pounds, .1-.2 better from the a/c, timing, and other mods, and the last .4 or so was from the weather...wow are you kidding first off i lost close to 500lbs, i advanced the timing quite a bit, losing the a/c is a rediculous help plus going from 15.3-14.2 is not a hard acheivement.