I have no idea if this will work on a Givi screen (though I have one myself which is covered in fine scratches so I might give it a go myself when I get the time) but when my dad's Laguna headlights started fogging (UV damage) I looked up how to fix it and the following cropped up multiple times on various websites, my dad was brave enough to let me try it out ... it worked perfectly
.
Instead of starting with toothpaste, you need to finish with it (or jewellers rouge if you can afford it) - basically you have to sand the scratches out.
!!!CAVEAT!!! - I have not tried this on a Givi top screen - only a car headlight. So DON'T take this as gospel - only as an idea worth investigating.Start with 6 or 800 grit 'wet and dry' and give the entire surface a good long scrub - it will go completely opaque and you
will panic
- but fear not padawan, for enlightenment rewards the patient...
Wash the crap off, and do it again with 1000 grit, and then...
(I've always wanted a legit excuse to say this) rinse and repeat - this time with 1200 grit, and 1400 - 1600 if you can find it.
By this time you will (should) have a very sore elbow, but will be able to see daylight through the screen - if there are any large scratches left , just repeat the process until you've got them out.
I'm not sure of the grit size of toothpaste but jewellers Rouge is anywhere between 2 and 3000 grit - if you finish with that you should have a completely restored clear screen.
- you coould also use T-cut or car polish as they are both very fine grained...
The problem you will have is (as is mentioned above) the outer/top screen is quite soft and will re-scratch as soon as you wipe any insects off of it. I'm not aware of any treatments which will harden the surface, but some may exist...
That's my tuppence worth...