For a tuned Spridget road car, convention dictates that a single DCOE be 45 with chokes of 34 or 35. Going to double DCOE dictates 40s with chokes of 28 or 30. There must be a good reason for it, but in my simplistic view, I don't see why there should be a difference in size. The volume of the intake stroke is constant, so each throat of the double DCOE setup will be supplying the same volume of an intake charge but half as often as the two throats of the single carb setup. So why should choke sizes diminish with more barrels that will flow less frequently? Why even bother with extra carb barrels?