There are 2 chips. One needs to be spliced in in front of the MAF. Supposed to change or trick the cpu and increase mpg and hp. Supposedly the MAF one will increase mpg 3 to 6 mpg and if you install the oxygen chip(in-line with the oxygen sensor-although you need 2 of them because 2 oxygen sensors) supposed to increase mpg 4 to 8 mog total. I have not done this yet but was wondering if it would be worth a try. Go to Performance Engine Super Chips ECU Power Racing Car Chip Tuning Flash Chips