I found that the airbox mod is worth doing: I taped up the back-side of the inlet with gaff tape. If you peer down the inlet, it's significantly restricted and from my eyeball I determined it's smaller than the TB inlet tube. I opened up the drivers side with an oscillator tool. I also removed the leaf guard, but it really doesn't appear restrictive. I have heard someone mention the term "turbulence" in reference to the leaf guard, but I doubt the turbulence reduced is enough to notice. When you consider the temperature increase developed by the compressor at the intake manifold, perhaps the tape does no good either.
But wait a minute: There is a very noticeable improvement in engine happiness! My right foot is happier! I grin more!
Your happiness may vary.