The length, shape, and size of the manifold which is the primary contributor, to the volumetric efficiency of a given engine referred to as the cake of the port, the finish is referred to as the frosting on the cake. The cake allows for the air to go from a pressure side to a variable absent of pleasure side , the air having velocity accordingly and is a value which allows carburation. After carburation accrues the next thing to enhance the fuel air charge is the animation of the fuel particles by increasing the turbulence of the air charge . A textured surface by bead blasting is a common practice to increase turbulance, how much it raises the H.P. depends on the builder, the younger ones seem to believe in texturing while the older guys like the polish mop. The modern engines do seem to have a little more mussel then the older ones so it boils down to a preference. Do I go with the frosting or not?
Max