Could add rattles, could mean they have ironed them out !!
And of course, if it comes with a tube of sealant so that you can stop water ingress buggering up the module that controls the lighting system, plus a couple of twenty amp fuses so that when you're half way across Europe and the lights all go out you can get them working, even better!
Aero? Don't make me laugh. Expensive car- cr*p build !
( Well, I have to be consistent don't I)

G