That tells me that even with louvering, most air is deflected away from the parts of the engine that may have been designed by Honda to cool the oil.
I know thousands of GL1800 owners have installed bellypans, but the idea of choking off cooling air that may be vital to the engine still bothers me.
OTOH, protecting the coolant overflow bottle, oil filter, and bottom of the sump is also desirable.
I'm torn.