My steps until now to reduce the noise:
-turn the windshield up-side down and maximum up
-added 2 plates and moved the Givi about 2'' higher(id I remember well) and keep the OEM screen at the bottom
at this point, I've seen about 30% reduction of noise and some buffeting
now the helmet: new one HJC IS-16 (I got it mostly for the drop-down sun visor) is quieter the old one, HJC Cl-15.
it has also the chin guard that helps a bit with the turbulence coming from the bottom part of the helmet.
I had a revelation last year when on a longer ride I used ear plugs....I could ride with visor up and sun visor down (summer, hot) up to 100km/h, very little noise and I can hear my music on Sena ( almost maximum volume); but I don't like ear plugs..
, it bothers me after about 2 hours.
plus the I cannot do anything with them once I have the helmet on...
I think I will try this quiet ride muffs....I still have my old helmet to do a test..