The only mod I really have is the 31s but I have the 4.56s to bring it back to stock gearing. Also, I am at 5k feet so maybe the thinner air helps a bit? Less wind resistance and less dense air intake. I keep the engine tuned to factor specs all the time. I use only toyota replacement ignition/tune up parts. My tires are street biased michelins and I keep them aired up. I use synthetic gear oil. I don't have a/c. Also, I drive pretty converservatively...I rarely push the engine hard unless going up a steep hill. The only load I usually carry is myself. Maybe all those things added up?