I got the 17 inch to replace the stock windscreen. It was dead easy to install and only took a few minutes. With the stock windscreen I had to duck down quite a bit to get away from the turbulence and I am quite short.
Now, when I am sitting up, I get a slight breeze on my face as if the AC is on low in my car. If turbulence is an issue, this is a great investment.Rating: [5 of 5 Stars!]