I've been dealing with the buzz coming from my '09 V for the last 300 miles (half the bikes life so far) and had come close to curing it, but not quite...until today!
I tried everything (foam under cowling headlight tab, foam around gauges, rubber washers around snap pins in black cowling, etc.) Everything was almost perfect...until I got the Givi windscreen. I mounted that bad boy and wow, a hideous buzz around 4000 rpm all the way up to 5500 rpm. I swapped back in the stock windscreen and it mostly went away. I thought about trying the disassembly of the gauge cluster and trying the drinking straw trick, but I decided to take the bike out one more time and track it down. While holding it at 4000 rpm, I started fiddling and put some pressure on the left side of the windscreen pushing up. The buzz went away. I found it!
I took apart the bike again on my lunch break today and attacked the windshield bracket. Here's what I did. I placed rubber washers on top of the windscreen grommets. I placed a 3//8" x 3/4" x 1" piece of weather stripping towards the bottom of the bracket (so it'd sit in between the windscreen and the bracket.)
I also pulled off the entire bracket and placed rubber grommets under it where the bolts hold it on.
One other thing I did, which I didn't see until I disassembled everything was I placed a very small piece of weather stripping on the bolt post for the bottom fairing bolt. The windshield brack "wraps" slightly around this post when it's installed (see the red arrow). There was a very small gap right there between the bracket and post, enough that I thought it might be causing the buzz I had. The weather stripping sits between this post and the windscreen bracket.
So after doing all of this...I took it back to work and OH MAN IT SOUNDS GOOD!!! Not a single buzz coming from anywhere up front!
I haven't seen this area mentioned before here so I thought I'd share in case anyone else is having problems tracking it down. But then again, sorry if missed it and I'm just posting redundant fixes!
btw, the pic is from an ebay auction. I forgot to take pics of my fix so I just snagged this for example's sake