The COBB Tuning Fuel Pressure Regulator Manifold Reference Relocation Kit includes everything you need to relocate the FPR reference line to a more stable pressure source.
This allows for moving the fuel pressure regulator's manifold pressure reference away from the #4 cylinder runner and into a plenum-based source, similar to the method used on the previous generation 2004-2007 STI. This helps prevent unwanted manifold pulsations from affecting the FPR as the plenum is a common area of the manifold that represents the average vacuum/boost of all cylinders rather than a singular cylinder.