The PPE High Performance fuel rail with Race Fuel Valve will block the fuel pressure relief valve. This eliminates the low fuel rail pressure DTC codes P1093 & P0087 (low fuel rail pressure during power enrichment) that are caused by insufficient PRV spring pressure. Replaces stock or shimmed pressure relief valve. This completely blocks the pressure relief port deadheading the fuel rail.**Not legal in California. This PPE part is not Legal in California nor is it (C.A.R.B. California Air Resources Board) compliant and therefore not legal in California for any truck that can be licensed for on Highway or off Highway use. This part may only be used for a pure race truck that is never driven or legal to be licensed for on highway or off highway use. This part may not be legal in your state as well and with this purchase you accept liability and you are responsible for any laws broken, fines incurred, sanctions taken against you for using this part on your truck in any state where not legal. PPE, MJD and our suppliers will not ship this unit to a California address. With your purchase of this item you agree not to hold liable or responsible, MadJack Diesel Performance, Pacific Performance Engineering and their suppliers liable for any damage caused by, fines for use of, or sanctions against you for use of this this non C.A.R.B. compliant PPE part.