I've been around motorcycles for many years and watched the industry struggle with noise control issues. Very few companies
allow unrestricted intakes due to noise issues, same with exhaust systems. The VFR is a noisy motorcycle due, in part, to it's
gear driven cams. I figure the restrictive intake is one of their efforts to lessen the overall engine noise. JMO of course. But I
also think Honda put a positive spin on it, just because that's what they do. Have lemons? Make lemonade. Have to restrict air
intake for noise purpose? Make it sound like you're doing it for a reason other than that.
No, I don't want to discount the information in Chapter 21, but there's only about 2 pages of that chapter that refer directly to the
operation of the flapper valve and snorkel. I'm not discounting any of the information in Chapter 21, I'm just saying the info about
the flapper valve and snorkel may not be the complete reason. What would be the purpose of explaining that it's there for mostly
engine noise abatement. If they said that, the first thing anyone would do is pull it all off. Look at what happens to quiet exhausts.
Again, there's lots of good information in Chapter 21, but very little mention/explanation of the flapper valve and snorkel. And the
reason there's not very much, is, IMO, because it doesn't really do very much.