not exactly sure if you are refering to me as justin, however i think its safe to assume that you are refering to my intake when you ask how i/we were able to come up with a 5 liter plenum design.

the intake was actually inspired by the JM Fabrications 1g 4g63 Drag intake, that yeilded exceptional power over the stock 1g intake. granted head flow designs and motors are apples to oranges, to me the theory of more volume the better in a turbo application remains true across the board.

so that is where this manifolds design came from. again as stated earlier, mikes port jobs on his lower intakes is bar none, and really wish i had that done with my plenum!