I don't think you would ever want to look through a windshield, especially in bad weather. Bugs alone on a road trip would make for sore eyes and possibly difficult conditions. Ideally is just over the top edge. the wind and air should break over the top of your forehead. Helmets make a big difference to as to felt wind and buffeting.

 

6', sit fairly straight up with khromewerks +2 sweepers bars and my 14" Windvest works much better than stock. CUTS DOWN on buffeting, but doesn't eliminate it.

I can now hear my radio at 1/2 volume on the highway too.

 

In the new 2011 Parts & Accessories catalog there is a new wind deflector available to stop the air coming up under the fairing into your face. The item is on page 343, Item H, cost $29.95. Item # 57000063....

 

I'm 6'3 and have the 12 inch Windvest. I also look over the shield. It works great.