Understanding flat top piston/valve?

[markjs]

So I'm building my 1322 up bit by bit and the subject of flat top valve and piston is one I don't fully grasp?  If I get one, I won't mess with making or modding my own, I'm not set up for it and Mellon Air has what I need.

I'm just trying to understand the concept?  So far all I know is the name, and that it makes the pump pump more air per stroke, so say 7 pumps with a flat top equals 10 with a normal stock valve and piston?

[Van]

  The stock set up with the cone shaped valve front and pump cup has excess head space at the end of the stroke due to flexing and not being adjustable. This means that some air remains trapped in the space between the cup and valve on each stroke that should have gone into the valve.  The flat top design eliminates most of this head space for more efficient pumping when adjusted correctly. That's how more air per stroke gets into the valve.