Welcome to extrame psi parts! Fuelab Fuel Pressure Regulator 51501 FPR -10AN 51501-1 BLACK. All FUELAB 51501 Series Fuel Pressure Regulators Feature. Precision pressure adjustment hardware. 1/8 NPT gauge port (for external pressure gauge, plug supplied). 1/8 NPT pressure reference port with supplied barbed fitting. 6AN return line port. All stainless steel hardware. Long life fluorosilicone diaphragm. Available in 6 different colors. We offer a 100% satisfaction guarantee. Product must be sent back uninstalled and in brand new condition. Extreme PSI is a family owned and operated organization that has been fueling the global import racing scene since 2002. We are your #1 source for In-Stock performance parts. Our Bensalem, PA headquarters is home to the company’s internet-based shopping website created explicitly for the car crazed, racing enthusiasts and the do-it-yourselfers. Safe & Secure Payments by.