You actually want a long smooth tube. the longer length gives the air time to settle and stabilise into a more laminar flow.
I agree also that you want a cold as possible air going into that tube.
The Manifold uner the TB is absolutely crap, but as nobody yet does a replacement we are stuck with it.
Best answer is 4 direct throttle body injectors (like the Weber Alpha kit)that does away with the whole lot but its very expensive
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