I actually did that at first too, I still have the part somewhere. Others have done this too. Should work fine. I'd block off the hole in the fender left by the one part though. I used an OEM plug like the pic it only cost like 4 bucks. Still even that part is a little restrictive compared to removing the gasket in the airbox:
Granted with the snorkus part in there the rubber will be expanded some but not as much as just removing it. It's the same for my 97 Legacy and a WRX I worked on.