Join Date: May 2018
Location: NW Arkansas, USA
FWIW, I am fully aware it is almost 100% anecdotal but, on a recent 2,500 mile trip with lots of 75/85 mph highway stretches, my Puig visor deflector eliminated all of the peak vibration and buffeting to the point that I could ride with the helmet visor open all the time without any noise/dust/bug strike issues.
But I continued to experience a lot of wind noise and, having read about the air dynamics from the fork area I first tried laying my hands over it then stuffing t-shirts without any difference. I eventually found out by using my hands that the wind noise was coming from underneath the helmet, around the ears area. Putting my hand over that area eliminated the noise and, still using my hand, traced the air flow back to the air deflected by the front cowling to either side, right around the front blinkers. The noise was exacerbated whenever side winds were present.
I am now waiting on the Arai XD4 helmet to be available as the Bell MX9 MIPS I was using has little padding around that area. Other things I am considering are a neck protector (both for safety and as a way to deflect the wind -shrugging my shoulders up had helped before- from coming up underneath the helmet).
The last thing I would eventually try is to purchase some lexan and mount it in those areas to deflect a bit more wind. My hand seemed to be enough but I have to consider that my whole riding angle had also changed when I stretched out and my arm was extended to boot.