Also, something VERY important that hasn't been asked and is commonly overlooked.

Are you shutting the motor off as soon as you lift from the throttle on a N2O pass, then towing the car back to the pits to do the plug inspection? If you are driving it back, and looking at the plugs after it has idled and driven back, the plug readings may not be indicative of what the engine did going down the track. They will be contaminated with what the engine did returning to the pits. This seems to escape most people when it comes to plug inspections.

Brian
EFI-Unlimited