I am probably the person you found on this site about the Slipstreamer 66 wind screen...I have not seen the review you were speaking of, but I can add to my original message that yesterday I rode north to Alamagordo, NM and returned (132 miles round trip). On the way home I hit an indicated 80 mph and could probably gone to 82 or so had I stayed on throttle. This was on my GTi300 with 5,200 miles, a Slipstreamer 66 windscreen, 14 gram sliders, and a 46 litre topcase. Otherwise, stock. And, I don't know where the other article stated that the mirror mounts were extra...mine came with the windscreen, and if the windscreen is too tall just trim a bit off. I'm about 6' tall, and I think it's a perfect height. My feelings about the Slipstreamer is that it's very inexpensive (under a hundred bucks, I think) and, to my mind, a very good design. I would appreciate one that was designed with the GTi300 in mind, but that's really not too possible at this time. If you'll notice the one Dave Harrington shows on the latest bit about windscreens, the brackets hang over the bright/low beam and kill switch...not a very good design, I think. And, the latest Kymco one that he tested is just too short for what I want.
Good luck with your choice...I would heartily recommend a Slipstreamer 66 over what else is out there at the present.
Karl U