Is it just about the direction of the airflow and size of the hole? Does the volume of the ball or bubble affect anything other than banger compatibility?
We feel the inside volume has nothing to do with the function of the carb cap. We feel the diameter of the carb cap is made to only match the size of the banger it will be used with. The larger the holes the more the air will flow. This all also really comes down to personal preference if you want a fast or slow hit