i just made a 800 mile round trip and i was only gettin about 10.5-11mpg thought that was pretty low.... i had vivian give me a trans. only tune.....i was towing an open trailer with about a 3k pound car on it so im guessing about 5k pounds total..... i got about 11-11.5 on the way back with no car on th trailer..... does this sound about right to everyone?