Modified it to produce an open area under the plenum (commonly called an air gap).

This design allows ambient air to pass beneath the plenum which has a cooling effect on the incoming fuel/air charge thus producing more power. 

This isolation also keeps engine heat from transferring into the plenum chamber. 

This manifold has several unique features such as a rear water crossover passage
which contributes to a cooler running engine, nitrous bosses and four corner water ports.