Granted hood temperatures would be a factor in helping keep it warm after a good amount of warm-up, but vapor pressure will vary significantly based on external temperatures. That'd be one hell of a time trying to monitor consistant pressure. As the bottle cools, the pressure will drop rapidly resulting in less air pressure at the intake. A serious eye would have to be kept on the Air-Fuel ratio with constant changes even @ WOT. Small volumes of CO2 wouldn't make that big a difference, but when you let out a good 15-20 second run on a bottle, I bet it would significantly affect it.