Ya there gas mileage blows.. I went from 26, to 30, heres how...
I have a five speed btw.
Cold air intake, bumped up tire pressure, about 2 to 3 pounds more... lighter rims.. thats all.. well I do have a fart can

but i dunno if that helped..
About the fuel chip, they suck..
I saw something on ebay i know some of the x-l7 dudes have used, and said helped... but i duno if it really works..
its a in essence a magnet you put on the fuel line that supposively seperates the molucules in the gas as to more effeciently use the gas.. again dont know if it works or not.