some people say you still need it, some say you don't. i would rather be safe than sorry and use an anti-siphon tank. or just get compressed air haha.

ahh....i see. where do you live?

input pressure varies from gun to gun. depends on what internals you have and if you have an LPR or not. But a good place to start is around 160psi IMO. Stock imps you should start around 180-200. Don't go over 200.

I've seen lots of Imp's run on Co2 over the years...I was at C.O. Paintball when the Imp was released and we sold tons of them to people and set them up to run on Co2. Couple of the guys who worked at the store had Imp's running on Co2 and they did fine, heck one of them was probably never rebuilt and really not lubed the way it should be and he played all the time with that setup....As far as them eating o-rings, keep them lubed and they are no worse than using HPA on it from my past experience...Co2 gets a ton of shots on an Impulse per fill as well since it expands so much inside the tank, I've seen a 20oz Co2 with an anti-siphon kit do just as well as a 68/4500 on shot count. Before the Imp alot of us at C.O. ran the old shoebox Shockers and we ran all of them on Co2..We built 68/3000 tanks and converted them over to Co2 with a Smart Parts on/off valve & an anti-siphon kit in them...That's the only way you could get any shots with one of them on a fill, the old Shockers used HPA like there was no tomorrow but did really well on Co2.
Set the bottle up right and the Impulse will run fine on it...As far as running them remote, you really dont need the Anti-Siphon kit if you run remote, the long remote hose works as the anti-siphon and keeps the liquid in the bottle...If you ran an anti-siphon tank remote the tank is standing up in the verticle position for the most part, the point of the anti-siphon tube in an on gun tank is to set it up so the tube is curled and pointing up, that way it doesnt pick up any of the liquid Co2 and send it into the gun...When on remote with the tank standing upright that's not a real issue...But do make sure the gun has the filter inside it for Co2 use.