...if you have a valve that can beat the predictions of "SOKO". The strings I've seen from actual self-regulating valves (e.g., my Disco) seem to conform to it pretty closely.
Pmin = Popt[1 - square_root(1 - M^2)]
Pfill = Popt[1 + square_root(1 - M^2)].
For a specific example, if...
Popt = 150bar
MVopt = 900fps
MVes = 25fps
Then M = (900 - 25) / 900 = 0.9722.
Pmin = 150[1 - sqr(1 - 0.9452)] = 115bar
Pmax = 150[1 + sqr(1 - 0.9452)] = 185bar
By the way, I'd be happy to chart the numbers for you, if that'd be more convenient. Just a simple column of numbers would be easiest to import into Excel.