Hi Dirk, the best size of a windshield depends on your size. If you are below 1,80, you should be ok with the MRA spoiler shield. Iīm 1,87m, so that the turbolences are very noisy. Thatīs why I cut aprx. 18 mm of the original shield. This helps avoiding noise up to 150km/h. Riding faster is still a noisy thing, I use earplugs... Hope ths helps. Rgds Flo