first you need a vertical adapter for a reg to go on. then you need a reg for it. i recommend a hyper3. i run one on my classic and have no issues and is very consistent. also if i were you i would look over the entire gun and make sure it works with no leaks. if you need some one to do the work for its not hard to find someone to do it. pm me if you need any more info and i also have the manual i can send you if you want it.