Originally Posted by Korruptio
Correct. Testing for this is easy: take off the mirrors and ride the bike, put back one mirror and ride the bike, put back both mirrors and ride the bike.
Original mirrors are causing the bad buffeting and wind banging to the helmet. Atleast for me (~185cm tall rider). I noticed it by accident when mirror got broken and it was more pleasant to ride than with both mirrors... Now I'm in process of replacing the original mirrors with something else. Probably short KTM foldable mirrors, they're half of the price of original KTM Adventure mirrors anyway so its not a difficult choice.
The same used to be true for the Suzuki Burgman 400. Drive that thing down a freeway stock and the windscreen would just bend and twist like crazy and it would buffet a helmet to the point that you could not see. The solution was pretty simple -- move the mirrors closer to the windscreen by just spinning them on their mounts 180 degrees.
OK, don't ask me how I know all this.