If you believe that, then I have a few dozen "Tornado" intake inserts to sell you!
Ask any aerodynamics designer -- there's no way any "swirl effect" would exist (even if the grooves did anything besides slightly disturb the boundary layer flow near the throttle valve) after making the right angle turn down into the plenum, over to individual runners, back up, over, and down the runner into the intake port, *then* through the narrow, high-velocity annular gap when the intake valve lifts. The *only* swirl effect is that which Ford already designed into the intake valve/combustion chamber.
i have the intake spacer between the upper and lower intake and it smoothed my idle out big time... also my car comes down from the rpms and doesent hang for as long.