Every BMW I've ever owned has needed an aftermarket windscreen.
There are several good options for the K1600, with the most popular being from AeroFlow, CalSci, and Cee Bailey's.
Lots off riders are having great success
with the full AeroFlow K1600 setup
AeroFlow makes screens in two different shapes (GT & GTL) that were designed to carefully control the airflow on both sides of the screen to provide a smooth, laminar flow effect. The GTL screen slopes back towards the rider so it can be full coverage, yet still be run down lower so you can see over it with the quite low GTL seats. The GT screen has a bit of a flip at the upper edge, so it can also be run just below your field of vision, yet still push the air up and over your head. This tends to work better for taller riders, or the taller GT seats that sit you so much higher on the bike. Both screens shapes come in various heights so you can customize it to your height, seat height, riding style, and needs.
AeroFlow has also developed AeroWings and AeroGards for bike's fairing that reduce the turbulence that comes in around the sides of the bike and dumps onto your hands and into your lap. These wings help with any windshield, even the stock BMW one, and allow for reduced airflow on the rider and passenger.
The CalSci K1600 screen
uses a carefully-developed shape and a adds a cutout vent to allow some airflow through the screen and up the backside, which reduces back pressure and turbulence. Many riders are happy with this approach, although some of them are still using the AeroGards and AeroWings with this screen.
The Cee Bailey's K1600 screen
is taller & wider than stock, with an added Gold Wing-style vent to get some airflow and reduce turbulence. The vent does help to minimize the dirty air spilling over the sides/top, but it kinda looks and feels like an add-on fix. Again, many riders are happy with this approach, but some of them are still using the AeroGards and AeroWings as well.
There are also screen made by Wunderlich
(who also offers hand
, and foot
(made from polycarbonate, like the stock screen), and 7JuRock
(who offers the cutout or the 'Wing-style vent), although these aren't quite as popular with the K1600 crowd. And some members have cut holes in or added vents to the stock screens, with limited success.
If it was my money, I'd give Paige a call
at AeroFlow and talk with him directly. He can set you up with the full package at a discount, and make sure you get the size and shape screen that works best for you.