Not only is it not likely to help, you also risk getting the track wet. Don't do it.

For drag racing, this would be cheap and effective.

I think it was DEI that sold a co2 intercooler sprayer a few years ago, would be way better than water.

Even cheaper and more effective is spraying it into the throttle body.

I play paintball a lot and have a 50lb CO2 bottle sittting at the house and have been debating on making a simple solenoid activated spray ring for the intercooler. Figuired it would only help for drag racing and not be of much use on track. The factory intercooler on my Jetta gets heatsoaked pretty quick and it would probably make a big difference. That sucker runs strong as hell on a nice 30 degree morning.

I am sure since nitrous is not allowed on track that they probably would not want a pressurized CO2 tank in the car when running on track either. The miata is for track days and no dragging.