The 3657 is designed for use with the 7135 Oval Port manifold. This kit will work with Pico injectors as used on the PN 3557 Pro-Flo XT EFI conversion kit, or with standard height injectors (2.50 o-ring center-to-center spacing) using the included adaptors. Unlike the fuel rail included with the PN 3557, in this kit all of the fuel rail ends are tapped for 3/8 pipe. There is no provision for our plug-in style of fuel pressure regulator. The customer will supply their own crossover and regulator. The fuel rails are black anodized prior to machining.