I had the CryO2 on a previous car. Itworks if you spray down the IC before the run. You do NOT want it to spray during the run, or get into the intake. CO2 will seize an engine, it is not like NO2.
And you can get get CO2 at any welding supply shop. They use C02 for some of their equipment. It is much cheaper than NO2 ($1/lb. vs. $4/lb.) hence why it makes a lot more sense as an IC sprayer than N02. Similar effects but much cheaper.