This Nissan Silvia fuel rail kit is specifically designed for the SR20DET S14/S15 OEM intake manifold.  Manufactured with a 0.69" large internal bore, the fuel rail can support all necessary engine power requirements. The rail is CNC machined from solid 6061 aluminum and black anodized for a high quality surface finish. The included phenolic spacers mount the rail to the OEM intake manifold bosses thermal isolation. The Radium fuel rail converts the OEM side feed fuel injector setup to top feed, allowing the use of high flow fuel injectors (not included). The fuel injector bores are 14mm ID. The kit is designed for specific upper and lower O-ring spacing, as depicted.