Ferrea - 6000 Series 35mm Standard Intake Valves - Mitsubishi - 4B11TSpecifications: Manufacturer: Ferrea Reference Number: F6294 The 6000 Series Competition Valves are designed to provide excellent reliability in an environment of high spring pressures and roller cams, at a budget price. They have higher fatigue resistance and tensile strengths than our competitors best offerings. To manufacture the valves we use our exclusive two step slow forging process using EV8 stainless steel on both intake and exhaust valves.