After 4 month and 13.5k km ride on bike this time. i say the air box is devil. Wind is the what will such vacuum in airbox and after it runs like crap. If zero wind days or wind is from back in ideal, it will like like a charm, no vibrations - d-am-n smooth. Now the bad, there is almost wind , so there are few days when you get ride that you do expect.
I can say no humidity,temperature,barometric pressure will affect so lot as wind.
It's probably related where you live too. As many of you ride open helmet, in my era, helmet with glass is not visible after 200km(day or two ride in my case by average), the insects will say hello, also they take care of my Richa leather jacket, it's always oiled.
Now my question to POD filters installers, does it make any noticable difference ?