There is a third ‘weather’ accessory that I recommend…
As mentioned above, I have the fender extender and a mudsling fitted to my bike. For those who’ve not yet invested, the fender extender stops the front of the engine from taking a beating from the road grime (wet and dry) that gets flung up by the front tyre, and the Mudsling stops a lot (not all) of the spray that gets thrown around at lower leg level.
I looked into this, back in 2014, when I bought my first 1200GSA (LC), because I couldn’t fathom why my lower legs (suit) were getting properly saturated. It was suggested by others, who delved far deeper into it than I did, that it’s a lot to do with the design of the bike and turbulences set up by motion at a certain speed.
To assist with the spray even further, for a brief time I fitted a Puig hugger, which pretty much stopped all of the spray around the lower leg area, but I didn’t like the circulating horror stories of the mounting bolt failures where it fits to the rear swing arm stay, so I took it off.
The accessory that I recommend, is the rear ‘crud catcher’ (a Cymarc product). It fits behind the number plate and is basically a small (width of the number plate), angled guard which prevents the rear rooster tail of spray that gets sucked forwards in the slipstream at a certain speed. Before I fitted it, even with the rear box fitted, I found the back of my jacket was getting wet. It wasn’t just rain that was wetting me, it contained grit and grime from the surface of the road.
If you look at the bike side on, you’d never imagine it would happen. Not with that rear tyre guard, the number plate projecting further back than the rear tyre, and the rear box… I suppose it’s just physics! Anyway, with the rear crud catcher thingy fitted, as simple as it is, it stops the slipstream spray ‘up your back’ from happening. Well, it does for me. So far, it’s been on all 4 of my GSA’s, along with the fender extender and mudsling.