... The multiple setup decreases the distance and the variance in distance from the A/F source (carburetor) to the cylinder. This promotes better cylinder fill ratios, and more constant A/F ratios among cylinders.
Jon.
Purely hypothetical question here.
Assuming one wanted to keep the single carb setup but was looking for improved AF balance...
If one selectively ported/polished the furthest cylinders, maybe not as much on 2 and 5 and left the centers original could that help in 'balancing' the A/F ratios?