hey rob.

if you can wait a bit, i will be removing the 2wd plenum cover and elbow sometime this week or next week and replacing it with a 4x4 one and could measure them for you by filling them with water.

that would be literally just the cover and elbow though, not inlcuding the inlet manifold at all.

anyway, the volume is nothing to do with how much they flow, rather it's more to do that a larger volume has more chance of equal filling to all cylinders.