99% of the "fuel saver power modules" are nothing but resistors that fool your ECU. They will end up causing more problems in the end then they are worth.
You want a good mod to get. Better intake filter, better flowing exhaust... and the BEST of any mod possible that is FREE!!!
A LIGHT RIGHT FOOT. Keep that foot off the floor, and accelerate a little slower, and you'll see a major improvement in your fuel economy. An electric supercharger will give you better HP gains that the stupid little resistor. And the electric "superchargers" they offer are junk.