I've tried lots and lots and lots of things.....
Possibly the two most effective things I did were to fit a Laminar Lip to the standard screen on my first GS and switch from solid foam earplugs to Alpine ones with filters in them which reduced the hammering noise in my ears.
Apart from that, I've made and fitted rubber gaskets that fit between the sides of peak and the shell, to damp down some of the vibration from the peak. On my original peak, I fitted a piece of screen edge trim along the leading edge and that helped to stiffen it. Most recently I fitted a Tour X 3 peak which didn't make any improvements and I've now stiffened that with thick jumbo sized paper clips bent into shape and stuck to the underside with the fuzzy parts of heavy duty Velcro. It's still not perfect but at least my eyeballs don't vibrate in resonance with the peak like they used to do.
However, by far the best thing I did was to buy a Shoei Hornet which fits me better than the Arai, is quieter and better ventilated. The peak on that does suffer from some vibration, even behind my current Z Technik screen but it's still considerably better than the modified Tour X.
HTH
