It says they're boosting to 10psi, in addition to the colder intake charge
The systems has regulators that step the air pressure down from thousands of PSI in the tank to a much smaller, regulated number at the nozzle that gets sprayed into the intake.
From the source company that sells the system:
> The very low temperature medium pressure air stream is then throttle one more time in the Electronic Pressure Regulator before being discharged into the engine air intake tract. The throttling effect that occurs here is small compared to that which occurs at the Mechanical Pressure regulator but, similar in nature.
The tuner can adjust the pressure that is being discharged into the intake tract, but that's not equivalent to the pressure in the manifold.
The system works by having the air expand rapidly in the intake, causing a rapid cooling effect.
The company describes it better on their own site: https://casupercharging.com/tech/#system-overview
EDIT: There is some mention of an "isolation valve" but not within the "Theory of Operation" section of the company's own description: https://casupercharging.com/tech/#system-overview
So there might be some scenario where the system shuts off the intake valve, too, but it's weirdly unclear from their own system description.
But to your point, I agree. Once the boost is achieved, the effects of the boost occur, because they aren’t really related to the source of the boost or how it is implemented. However, systems that use the engine for power like turbos may lose efficiency compared to compressed gas at the same boost level, depending on how much the gas system weighs compared to your turbo. It’s an interesting idea, especially for drag racing.
Yes, they put in the energy to compress the air 'offline' and then have that free to propel the vehicle. The cooling of the charge also improves the efficiency, the useful energy output is proportional to the temperature difference before and after the combustion.
A high capacity intercooler would be an interesting experiment also in utility vehicles.