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.
Reference the chart below to be sure the proper fuel rails are ordered.
The "conversion" fuel rails convert the OEM side feed fuel injector setup to top feed allowing the use of high flow fuel injectors (not included). The fuel rail injector bores are 14mm ID. Manufactured with a large internal bore, the fuel rails can support all necessary engine power requirements. They are CNC machined from solid 6061 aluminum, black anodized, and laser engraved for a high quality surface finish. The fuel rails are compatible with all fuel types including popular alcohol mixtures such as E85. 
The four billet injector seats are anodized and laser etched and provide a sealed receptacle for top feed fuel injectors. The seats are designed for injectors with 14mm lower O-rings.
20-0568-02 FUEL RAILS, TOP FEED CONVERSION, SUBARU EJ
VEHICLE COMPATIBILITY
04-06 Subaru WRX STi (USDM)
04-05 Subaru Forester XT
05-06 Subaru Legacy GT
04-06 Subaru Legacy GT (JDM)
05-06 Subaru Outback XT
FUEL INJECTOR COMPATIBILITY
Do NOT purchase "WRX Fitment" injectors. Read below regarding injector fitment information.
Below are some of the many fuel injectors that are a direct fit:
Injector Dynamics ID1050-XDS-34-14-14
Injector Dynamics ID1300-XDS-34-14-14
Injector Dynamics ID1700-XDS-34-14-14
Injector Dynamics ID2600-XDS-34-14-14
OVERVIEW
Each fuel rail features three 8AN ORB threaded ports (6 total). Press-fit spacers are included to thermally insulate intake manifold heat transfer.
INCLUDES
-Black Anodized Laser Etched Aluminum Fuel Rails (x2)
-Green Anodized and Laser Etched 22mm Injector Seats (x4)
-Thermal Insulating Press-In Spacers, 15mm (x4)
-Stainless Steel M8x1.25 Mounting Bolts (x4)