This is a split intake where the #1 and #4 plenums and the #2 and #3 plenums work together.

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The Ford 2.3 turbo firing order is 1-3-4-2. So when #1 is open, number #4 is closed, the same for #2 and #3. Since they draw from the same part of this modified plenum a larger available volume is created. By creating these pairs, one valve has more air to fill it at high velocity and low turbulence. This intake will let one valve have twice the amount of air closer to the valve when it opens. It will also maintain much better velocity than the gutted upper will(My gutted upper was really bad at low end response). Since the air is split in the area behind the throttle body where the air is still flowing straight, the volume is split in half and is more laminar. This will give one opening valve twice the amount of air without the turbulence caused by gutting the upper. A gutted upper lets all the air head towards the back of the upper intake and cause lots of turbulence. This should help the flow maintain velocity and still have good low speed response. I know that my car has very good low speed response.

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Each intake valve will have twice the amount of air available when the valve opens through a shorter runner without the turbulence of a gutted upper.

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(Idea stolen from RS450's 390 HP Merkur)