Not more powerful than CO2 though- CO2 operating weapons usually have an extremely high muzzle velocity, meaning they can't be used at sites in some cases; and even if you could somehow regulate the FPS with some sort of valve, sites still wouldn't let you use it, since it's CO2, and there is a large mistrust of CO2 weapons.
TL;DR: CO2 weapons are not trusted by sites because they have a massive muzzle velocity, however they are good for target shooting