Magnafuel MP-9433 Fuel Pressure Regulator 4 Port 4-12PSI 10AN Inlet 4 6AN Outs. Unlike many fuel pressure regulators that allow pressure to drop during sudden changes in fuel demand, MagnaFuel carbureted racing fuel pressure control units supply high performance engines with a steady diet of fuel. They feature exclusive pressure control units that control pressure drop during initial launch, gear change, or nitrous activation. They’re available in 2 or 4-port configurations with 1/8 in.