The following is taken from INTENSE-Racing'* website on this page
"Should I purchase an IAT Spoof Module?
The Intake Air Temperature module is simply a resistor packaged impressively and marketed to customers who don't know any better. These can sell for as much as $25 and many are lured into purchase by its low price and easy installation. It tricks your PCM into thinking it'* cold outside and therefore 'optimizes timing'. In reality it does little to nothing and cannot change commanded timing by more than one to two degree (and that'* on a hot day where you probably can't use the extra degree or two of timing advance anyway). Save your money and don't buy it. If your curiosity gets the best of you, buy an 8k-Ohm resistor from Radio shack and save $24.50.
Simply put if you want to try to spoof your pcm spend the 50 cents and try it out without someone getting rich lying to you.
1998 SSEi The Executive Hauler
Built Trans w/ 3.29s, P&P Jenny 5, S1X cam, Silver TOGs, Northstar TB & LQ4 MAF, FWI, Dyno tuned, #60 injectors,Oil Pressure Kit, 2.9-3.4MPS, MagnaFlow exhaust, 3" HF cat, MSD Coils & 8.5mm Super Conductors, AeroForce, only Sunoco 94, 100