I've seen this mod on several threads before, but I didn't want that big hole in my air box to remain open. I do bury my headlights in mudholes several times a year, so I want to be able to close it back up before going wheeling. So, I put a hinge on the plastic plate and secured it with a strap. Put some foam tape on the plate to add extra sealing when closed too. Now, if only I can remember to pop the hood and close it up before going wheeling!
By the way, I noticed quite a difference in power by opening up this space in the air box...especially when getting up to speed on the interstate on-ramp. It responds much better when I hit the gas.