Radium Fuel Rails - GM LS EngineManufactured with a large 0. 69" internal bore, the fuel rails can support all necessary engine power requirements. They are CNC machined from extruded 6063 aluminum, black anodized, and laser etched for a high quality surface finish. All end ports are machined with 8AN ORB (3 4 16 female) threads. The lower center ports can be used for optional adapters and are also tapped with 8AN ORB (3 4 16 female) threads. The kit features specifically designed