...The 914-6 GT competition engines used 906 twin-plug heads which were provisioned with larger intake and exhaust valves. The 906 intake valves were 45mm in diameter, sodium filled and 111mm long (approximately 2mm shorter than the 1969 911S). Made by ATE 3056.
914-6 GT Twin-Plug Head Valves - Exhaust and Intake - Photo 1
914-6 GT Twin-Plug Head Valves - Exhaust and Intake - Photo 2
Porsche NOS Factory Original 914-6 GT Twin-Plug Heads - Valve pn 901.105.404.03
Porsche NOS Factory Original 914-6 GT Twin-Plug Heads