how much head flow to justify dually carbs?

Can't hardly beat the old Weiand tunnel ram for badass torque production. Wish mine would fit under my 6 pak hood. http://www.hotrod.com/techarticles/hrdp_0801_mopar_intake_manifolds/mopar_performance_manifold.html http://www.moparts.org/Tech/Archive/bb/8.html