Sometimes, the smallest parts can make the biggest difference in your Duramax build. This Dual Fueler Race Valve from PPE replaces the pressure relief valve on your factory fuel rail to allow for an additional feed line for a 2nd CP3 or for a dual feed setup on a single CP3. The fitting specifications are M20-1.5 to M14-1.5. This is a fitting only, feed line is not included.