Compressed air. Its based off of a paintball gun tank. They use 3000-4500psi tanks all the time and much closer to your person, lol.
Love that nitrous plate on the mani... Pretty sweet! I tried to use that once. I got it all installed, and ripped it out when the RPM window switch was nit powering up. I assumed it was not wired properly (obviously) so I said F IT>