The PPE Fuel Rail Plug (heat treated SS construction) replaces stock or a shimmed pressure relief valve. This valve helps maintain fuel rail pressure during full throttle driving by completely blocking the pressure relief port (effectively deadheading the fuel rail).
The perfect companion to the PPE Fuel Rail Plug is this Viton O-Ring. It is made from high quality, chemical resistant Viton rubber. This ring is better than the stock o-ring and will last longer, too!