Tomei adjustable fuel pressure regulators for EFI engines utilise an extra light weight diaphragm assembly that provides excellent pulsation dampening; to dampen the pressure spikes caused by high flow fuel pumps and cycling injectors (especially non-factory high flow fuel injectors). Tomei fuel pressure regulators are designed to provide the correct fuel pressure for any high performance fuel injected vehicle. Suited for use on vehicles making up to 400HP. These are a proven top quality regulator!