Gnil:
Grant:

For the uninitiated, some may think that throttle butterfly is the only one (but there are 6 more) blush

Would be nice to see them Smiley  

I wonder what that ''tweeter '' looking thing in the middle does exactly . Would imagine it is some kind of a sound enhancer . 

When I consider the oblong piece below the butterfly, I think it is there to create negative interference for the dominant frequencies generated at RPM for typical road speeds. This way you do not have resonances at slower driving speeds. This is merely my speculation based on its cross sectional and vertical profile.