@dusan, i can see what your saying its barely measurable, but if you locked flaps in full open position i can still see them causing enough restriction in that runner to cause a velocity variation in the two runners to still create swirl.
The swirl flap runner is smaller anyway, so even no flap in there and the velocities of the two inlets wont be equal and so swirl to some degree.
I dont think swirl is an invention for power or torque, but emisions.
The manufacturers are trying to burn all the charge as efficiently as possible.
Swirl seems a very good way of mixing air/fuel.
On tdi forum theres been a lot of cylinder head porting and testing development and they seem to think they need to keep swirl , although it us created by the inlet design and shape on those.
Im sure manufacturers did back to back testing with and without a flap but if they had a measurable improvement of less soot, less nox, more efficiency, same hp for less fuel of even 1% , then i think they would go ahead and use it.
That tdiforum thread(8v but theory still applies, infact 16v looks harder to make swirl, hence nasty add ons like flaps)
Also in the pic top of thread, there appears to be some releif in the head at 3 0clock point around the valve, similar to the vw heads but nowhere near as big
Unless this is optical illusion from angle.