All cylinder work is smoothed to achieve maximum airflow. A template is used to match each cylinder in an engine and provide consistency between engines. All parts are matched for flow from the Carb Boots to the Exhaust Flanges.
Crankcase is opened up to allow flow from reeds / intake to enter base of transfer ports. This improves bottom end torque and acceleration - reduces bog and hesitation with large carbs. Big help at high altitude, and in deep powder, for snowmobiles.