PORTS AND FITTINGS
The fuel rail ports are tapped for 8AN ORB.
Appropriate fittings must be selected based on the specific application. Ample space around the fuel rail port(s) is necessary for larger accessories such as fuel pressure regulators, fuel pressure gauges, and fuel pulse dampers. To verify clearance, the dimensional drawings on the product pages can be used as a reference guide.
These Radium Engineering fuel rails are compatible with the VR38DETT engine found in the Nissan R35 GT-R. They are machined from 6061 aluminum and anodized black for compatibility with all popular fuel types including E85. Manufactured with a large internal bore, the fuel rail can support all necessary engine power requirements. Each rail has four 8AN ORB ports (2 end ports and 2 top ports for a total of 8 ports). 
The fuel rails mount with insulating spacers and washers for 100% fuel insulation from the hot intake manifold. The unique lower intake manifold mounting points permit shorter less restrictive rails. Additionally, the OEM injector clips can be reused, as shown below.
With 4 ports on each rail (8 total), it is easy to add fuel system accessories such as a pressure transducer, fuel pulse dampers, etc. There is also opportunity to plumb the fuel rails in parallel or series.
As shown below, the base kit (P/N: 20-0556-02) includes ONLY the fuel rails and associated mounting hardware. NO FITTINGS ARE INCLUDED.
FUEL INJECTOR COMPATIBILITY
This fuel rail is compatible with factory or OEM equivalent fuel injectors. If upgrading fuel injectors, consult your aftermarket injector supplier for details. Radium Engineering cannot specify any further injector dimensions other than stating ‘OEM equivalent’.