[quote=mjhcobra;1288734]Below is a PI intake and it does not have the 4 separate holes.
I would guess that the open wedge plate would not affect performance with the intake.[/QUOTE
On Chevrolet BB motors it's an old L88 Chevrolet Power Book trick to mill out the center divider on the plenum of the factory aluminum dual plane intake. Doing so sacrifices some low speed torque and response but typically boosts upper range HP. On the BB Chevrolet the carb usually has to be rejetted in a staggered pattern - each bore a different jet size - to optimize it.
Using on open spacer on that manifold will be essentially the same thing as milling down the divider part way - it will allow the two separate plenums to act somewhat as one larger plenum. The above is the type of effect you can expect from doing so. The odds are you may suffer a slight loss of low speed performance/response but in a light car like the Cobra, you probably won't even notice it.