I'll spit out the little 400 knowledge I have....
Some of the guys use a Buell Flyscreen.......pretty cheap here in the US, not sure about Italy. You can get them from BUELL-Harley dealers.
I think you have to modify the mounting hardware, or make your own.
There are a lot of FLYSCREENS that look good on a 400....a lot are from European sources. Givi makes some decent ones.