Originally Posted by Zodiac R279

Well I agree that it is not necessary for an engine that is lightly modded, but it is a good piece.

The Taper is there to act like a funnel to streamline the air charge.
Take a common warter hose for example. remove the nozzle on the end and turn on the water FULL blast. water comes out but with no force no velocity. Now take your thumb and cover the end of the hole half way and the velocity increases. Now remember fluid and water have the same properties of flow.
In the intake Charge Air Velocity is a bit more important than Volume of Air.