Look into the Dual plenum intake manifolds that audi used on their group b cars. If you have a "central" plenum with two slots i it (one for either bank) it will even out the flow and pressure very nicely. Make sure the throttle body opening and the slots take up the same amount of area however.
I've run CFD on a couple different manifold designs incorporating this and it helps equalize flow to each runner immensely.