i just called shane at bilstein tech because i couldn't remember why i mounted them up.
you are correct you can mount them either way. however, they recommend you mount them can up
to keep the can out of the dirt, as much as possible. there are some circumstances where they would
recommend them down. but that's few and far between. for our purpose, jeep, mounting up is correct.
also, on any race vehicle, dirt, i have never seen them mounted down.