The 1/8" NPT auxilary port can be used for monitoring fuel pressure, temperature, etc. The Radium fuel pressure gauge 20-0029 is commonly used. An included preimpregnated PTFE plug can be used if this port is not needed.
Radium Engineering Fuel Pressure Regulator with 4 Bar Bosch Regulator 20-0010-01
Radium Engineering Fuel Pressure Regulator Housing Body Only (20-0014)
Radium DMR-RA Direct Mount Fuel Pressure Regulator -8 AN ORB Black 20-1623-00
Radium RA-Series FPR Fuel Pressure Regulator Kit for Subaru STI 08-21 EJ257
Radium 20-0014 Fuel Pressure Regulator with No Top
Radium 20-1623-01 DMR-RA Direct Mount Fuel Pressure Regulator -8AN ORB Green
