Nitrous plumbing A1A...??..

The fuel side of my system is metered by a 1/8" pipe nipple with a Holley jet pressed into it. Basically drilled out one end of the nipple to a size that allowed the jet to be pressed in and then screwed that nipple into the nitrous plate. I see Holley jets as small as .040", you could "T" both sides of your fuel system into a Holley jet with about the same area as two of your fuel jets, and let them flow thru a return hose back to the supply tank.

Grant