I believe the windscreens work quite well at stoping a lot of the buffering. With the windows down I'd say there's around a 30%-50% improvement and with glass up closer to 75%. I can actualy feel the heat comming from the vents now!
Here's a few other designs......
http://www.windblox.com/styles/chrysler_crossfire.htm

http://www.topdown.net/chrysler_cros...windscreen.htm

http://dynamicautoconcepts.com/ProductDetail.aspx?ID=3

http://www.myroadster.net/mb_results.asp?model=CCF&class=Crossfire&category= Crossfire+Windscreen

http://www.wyckoffchryslerparts.com/chcrcowi.html

http://www.chromdesign.de/eframe.htm