[CREWZIN]

Those aren't "chips", no matter what it says. They are resistors that connect to the IAC and fool the computer to think there's cold air coming into the throttle body. The computer adds more fuel and advances the timing a bit. You get the same affect when you drive your car in the morning with the cooler air than in the heat of the day. The "chip"/"resistor"/"module" (whatever they want to call it)is connected all the time so even at idle, the computer is feeding more fuel into the engine so down goes your gas mileage.

...and as MG already said; too good to be true! The numbers are exaggerated.