Yeah, NME's do suck like that. The regs are not all that high flowing. If you would like check out my thread. Its the NME Help Thread
and I am sure it would help you out. If you set your regs right, and get your dwell right, it should only fluctuate about 5ish psi. But 80 to 70 isn't to bad, just could be better. Well check out the thread, I am looking for newer quesitons to post in it so I can help more peeps out. Hope I helped.
NOTE: I have heard that people have problems with HP tanks. I haven't had one yet, but you may give that a try like loser suggested.