Are you looking at one of those "performance chips"??? 20hp in 20 min for $20?? Avoid those like the plague. It's simply a resistor that you put in place of your intake air temperature sensor. The resistance of it theoretically makes the sensor see super cool air coming in, and the ECU will add more fuel and possibly advance the timing to compensate for this 'falsely dense air'. This may give you 3-4hp for a short while, (3-400miles) until all the extra fuel that's being wasted burns up your oxygen sensors, fouls spark plugs, and wreaks havok on your gas mileage. Then you've got $100+ in fouled sensors to replace.