The man is asking for a reg, buddies, not for "is a reg usefull or not?" !
I personnaly have a Bob Long, but you could also use a CP or any Cocker reg (assuming each cocker reg are the same). A stock phantom will allow you to come down to about 600 psi, if you mod the internals to go even lower you'll be stuck at about 400-450 psi.
By the way for people's knowledge, IT IS pretty usefull to reg a phantom when it comes to tournament, whereas it is totally useless at recball.