From my experience with several windshields, and experimenting with lowers, I have found out that the majority of buffeting is caused by airflow from under the headlight coming up over the gas tank. I would assume that this might still be the case with a batwing fairing. I have had two of them on bikes many years ago and they worked fine, but those bikes did not have the "under the headlight/over the gas tank" airflow buffeting problem. All that I am saying is, is that it might be very important to consider blocking the airflow beneath the headlight as well, or you may still find a lot of airflow behind that batwing fairing anyway.
my earlier posting 
