What Jon has posted about the resistors have been used time and time again...in our tunes there is a IAT table the directly related to amount of timing added or pulled vs the amount of air coming into the motor... 750ohm resistor tricks the pcm into thinking the IAT's are 149* so therefore you go to the 149 column and just put a -6 (Jon's case) to have it pull 6* of timing and when you activate the nitrous it then activates that relay and that turns on the resistor and then the pcm sees the 149* IAT