I was poking around under the hood of my Si coupe and noticed there's no clamps holding the rubber boot at the top of the intake resonator where it connects to the airbox. So I moved it around a bit and it pops right out of each end with a few seconds of wiggling each way. Removing this leaves about 2-3 inches of open air (not-fresh air, but hot engine air of course) in front of the airbox opening. I would imagine removing the intake snorkel/resonator unit completely would sound pretty similar, maybe slightly louder. Below 3500 rpm or so, there's no real sound difference. Around 3500-4000 though, it definitely is louder. Maybe not in actual volume, but it makes a pretty nice, surprisingly lower-frequency growl that wasn't there before.
I sit in traffic quite a bit, and I don't like the idea of the airbox sucking in that hot under-hood air. So I'm popping it back in, but at least I now have a pretty good idea of the difference removing the entire unit would make.