heh,maybe im crazy,,but y not use the propane as a cryo setup??yea iknow ,,boom,,,,,,,,,,,nos (naws,thanks f+f,sheesh,losers)would be "gentler" than propane,,being the nos is basically oxygen to a diesel,,,,,,,on the propane cryo,,it would be cheaper than co2 wouldnt it?

?figure out a way to get it away from lots of heat,,,,,maybe thats a little nuts,,,,idunno