The whole project started one day when I rode my friend IRISEP's bike with a GIVI screen. That thing really SUCKed, it sucked the air out of my jacket that is. It was really cold, and very disturbing, so with his permission and Todd VELCRO's tools I went at it (I used to make these things by hand... it's the same way for two seat airplanes, a long time ago). The "FIX" worked, the turbulence is less and the sucking is gone.
The principle is the air gets accelerated via the "naca ducts" and equilizes the pressure (suction) so no more funky turbulent air is created.