Now mine are up. They were down. Parts diagram inconclusive. You?
You can mount them down, for that aggressively cool cafe-racer tight fender look.
Or, you can mount them up, for that scrambler-esque fender gap that lets folks know you mean business.
In a less hyperbolic reality, down makes the fender and tire look more 'normal' to me,
but it occasionally makes really disconcerting noises when a sticky tire picks up some debris and drags it through.
Carbon fenders make a lot more of those noises than the plastic ones.
Up, there's just more debris clearance.
The plastic fenders are a bit flappy, and do drag on the tire, so up would help combat dragging.
For me, the answer is probably down.... I think the question came because I must have kind of noticed a change...