It probably wouldn't hurt, but a cage would need to be built to keep it open, and there's not really room for it on the stock system.TI wonder if installing an Injen Hydroshield over the intake opening would solve the problem.
In other news, I checked my airbox again today after heavy rains last night and it was essentially dry. It's possible the Air Horn drain was clogged and cleaning it out fixed the problem. New filter should be here tomorrow, so I'll keep an eye on it.
I don't like the possibility of a $16K bill because it rains.