Are you using a 3 or 4 port MAC valve? Going to a 4 port would extend your range as far as duty cycle goes without having to install CO2 or compressed air.
I was looking into a compressed air setup that way I didn't have to get c02 bottles filled, just more weight and draw on the electrical system. But ultimately I'm not sure if I'll be going much over 10psi until more safety equipment is added to the car.