the output pressure dial for either regulator goes to 6 bars = 81psi.
As mentioned, the output pressure dial indicates the working pressure only. I would assume it is ~30 PSI as mentioned, since you would need that pressure to work with the atomic diffusers that GLA sells.
Paintball tanks are at 3000-4500 psi if you were to just hit that little release valve on the tank... I don't know about the big co2 tanks though...
I find this hard to believe. Perhaps 800-1200 PSI, like most CO2 cylinders, sure.