I've been running open k&n's with outwears on them. If any water drops on them the engine starts to rev high and lean out. If I get to much water it will kill the engine. I then have to pull the filters off, dump the water that is inside the filer out, clean out the carb inlets, start the bike up and then dry the filters out on my exhaust. Takes 5-10 min's. Its a pain in the ass when you have a large group of riders and they have to wait for you several times.