I bought this last week, installed and tested yesterday for a few miles on the Palisades Parkway in NJ. It made quite a difference in wind noise and helmet buffeting. I started at home of course, local streets where you could not really tell any difference at all. I wore a HJC IS Max modular helment so it's noisier than a full face to begin with.
I then took it to 9W with speed limits of 40 mph, but went up to around 50-55 mph, with the visor up. Now, I could tell the add-on was doing its job. I turned my head to the left and right as if to change lanes to see if any change in wind effects on the head. Pleasantly surprised... there was none.
A couple of miles down I get to the entrance ramp to the Palisades, as we call it here and there I went... 55, 60, 65, 70 mph! With the spoiler about an inch and a half above the main windscreen (givi 410st) and the visor still up, I was amazed how there was quite a reduced amount of wind noise in the helmet, and impact on the my head. I again turned my head to change lanes, and no buffetting. I returned to the right lane as my exit was about a mile away, still at around 65-70 mph and all is pretty much like riding in local streets. This is the first time that I could hear the engine humming clearly more than the wind noise.
The kit came with both the clamp on and the bolt on. I did not want to bore holes on my main screen at this point so I used the clamps. Assembly was easy, except for one minor thing with the clamps which was my fault... I positioned it the opposite direction, but after looking at the pix in the instructions (who looks/reads the instructions?) I corrected it.
I made a stop at a scenic overlook to catch the view of the Hudson, which also gave a chance to check the install. I might not have tightened it all the way in the garage ( I was afraid to over tighten and break something as I sometimes do on farkle installs)... it needed a couple of turns of the screws on the clamps attached to the main screen and the brackets attached to the spoiler.
Adjusting the spoiler to find the "sweet spot" is done by a simple turn of the brackets in a ratchet fashion, both up and down with an option to change the angle as well.
The the whole package, except for the screws are all plastic of what appears to be good quality and the bracket assembly method is a series of inserting one part into another, which looks pretty secure.
Overall I am more than satisfied with this add-on, but I will update in the future to see how it holds up.
UPDATE: I should have mentioned that my V is 2013.