you are on the right track with upping the tire pressure.
i did a little test by blocking the upper grille and the SGII said i gained about 1MPG on at flat road going 60mph. but i took it off because it didnt look all that great...especially on a new car.
http://ecomodder.com/forum/showthrea...-log-6905.html
you could also lower your car if you are into that which will help mileage some.
i just bought the Civic hybrid engine belly pan, hope it helps some
