[Xringer]

I'm not sure. Since it's sitting in front of the windshield, does it really add to the frontal area?

The main selling point is, these things don't intrude down into the engine compartment
and I think (at speed) they may actually suck air out.

It would be nice, if one could use the intake and hood-hole size to balance the amount of air flowing out of the vent, so it matched the speed of the air flowing around the outside of the cowling..