Well, atmospheric pressure is 14.7 psi, so remember that pressure * volume will be constant for a given temperature. 125 psi * x = 14.7 psi * volume of tank.
A supercharger—such as a turbo—compresses air. Compressing air heats it. Heating air makes it expand. This is a Catch 22 inherent in supercharging. So rather than thinking of quantities of air in ...