Most of those ebay chips trick the IAT sensor using a fixed resistor to advance timing to a certain degree, therefore "generating" power by fuel enrichment proportional to the GUESSED advance in timing that resistor pulls. The colder your IAT "sees", the higher the advance, the possibility of more fuel, etc. But the bigger the guess, the higher the advance, this could literally bother your knock sensor, and if bothered too much and the knock sensor fails? Say goodbye to your motor. For what? 3-5 HP?

That's one way to go.