That's good to know. I've been thinking about putting one on mine to send the mogstink up over my head when I'm working near it.
The upright stack actually has a mushroom bottom to it, then the tail from the box goes into this mushroom WITHOUT TOUCHING THE SIDES, this means the water doesnt go down into the box, instead it goes down the sides of the mushroom and drips off

if you have an upright exhaust it needs to flex freely, forgot to mention that, if its just a normal tail pipe it literally bolts on.