Ponder this, and its only a thought. Could there be any benefits from just a one way valve on the pressure line from exhaust to tank? (no regulator) You would think that any pressure built up would be lost, lets say when you throttle down. A simple valve like this would keep any pressure in the tank from escapeing. In low pressure spray equippment there is such a valve for this purpose. It's about the size of a dime and would accept standard fuel line. I do not have a regulator. If it regulates pressure thats one thing, if it acts like a small fuel pump thats different.