Kelford STD Size Competition Plus Exhaust Valve Set of 8Ferrea Competition Plus Valves have built a reputation as the industry's most reliable extreme duty valve. To manufacture the valves we use special aerospace quality alloys, including the EV8 Z18, which provides high tensile strength. An exclusive two step slow forging process ensures proper grain flow and virtually eliminates any damage to thematerial structure. The valves are then heat treated and stress relieved over a 48 hour period, which is the