Right'o Supercharged, ive got yer!
gosh its pathetic isn't it?
Fruitbat, the only thing im can compare that type of conv ersion too, is on bike manifolds and systems that were 4-2-1 , or 4-2-2, to begin with, then "Race" versions were often 4-1.
Cobra,Eagle,Vance and Hines etc were the main culprits, but typically the american brands, and as such were only interested in very top end drag race power, the midrange really suffered, and was really hard to try and fuel back the whole it left.
whereas the cheaper but less special micron etc, 4-2-1 gained everywhere you wanted it too, and picked up some top end aswell, and were dead easy to fuel for to boot.
an car inline/transverse four ( a'la 2.0 TS) where the gas pulses are closer in the pipework due to the shorter headers, can still work as 4-1, but would very likely still produce a better road torque as 4-2-1.
does that help any?