Increasing your engines efficiency is a major way to improve performance and horsepower; the addition of performance-oriented aftermarket heads can greatly improve your engines output by enhancing airflow and combustion efficiency. Specifics and Features: Dual pattern valve covers will accept either center bolt or perimeter bolt valve covers This cylinder head does not have 400 stem holes. May require drilling if necessary Valves, Springs, Retainers, Hardware not Included Intake Valve Diameter: 2.020" Exhaust Valve Diameter: 1.600" Intake Port Volume: 200cc Combustion Chamber Volume: 64cc Intake Port: Square Exhaust Port: Square Pre-Drilled Accessory Bolt Holes 23 Degree Intake & Exhaust Valve Angles 3-Angle Valve Seat Lighter than Iron Heads. Each Head weighs 10.33kg Spark Plug Angle : Straight Includes: 1 X Cylinder Head