[petrolhead]

That's the chunk of metal I was eyeing. Something needs to replce that to mount the fairing and mud guard to. Also the front piece where the instrument cluster mounts to, can take some chopping.
I don't like too loud cars or bikes either. If you go fast enough, you can't spare any attention to the sound quality anyway.

I measured the holes of the airbox inlet pipe, 12x29mm. My calculator says that's equal cross sectional area to two 21mm throttles. So yes, its possible it's a restriction.