I just drilled a ring of 1" holes at the very top of the bottom section of my air box to allow air to come in from all sides when offroading. May let some warm air in, but who cares, lol? I'm not a racer.
What it's for is to make sure that water that slams up against the front of the air box can't cover the only inles. Since I can draw air in from any side around the top, it minimizes the chance of taking in much water. It has to rise all the way to the top of the airbox, and surround it, before air is cut off.
A look at my avatar indicates why I need it, lol. A snorkel is on the bill for the future, but I haven't done it yet. That deckplate is a great idea for a "snorkel bypass" so you get air when not using the snorkel. thanks for the information!