Speaking with M3 Tech Support today on the phone about low pressure the tech had the following recommendations:
* AKA Tornado valve
* AKA Lightning bolt
* AKA Sidewinder regulator
* Mill out the verticle regulator (drill the holes larger)
* He said he also milled out his low pressure chamber
* He did not specifically mention changing springs, and I forgot to specifically ask
With the above setup he says he runs 225psi @ 280fps.