Isn't it weird. When I do that (standard screen or OEM touring screen), I notice no buffeting airflow up the forks - in fact very little airflow at all. Why would this happen on some bikes and not others. I can't see how the rider's size or position could affect this bit of airflow.For those who haven't tried it, I installed one of the commercially available ones and it made a huge difference. No more buffeting of my head side to side at highway speed.
If you are unsure, place your hand over the gap at the front of the tank while riding at highway speeds and note the change...