the, idea of them is smart - swirling the air would help it go around turns, in say... an intake manifold in a car.
but the effect would be so little, you wouldn't even notice the difference in power or gas mileage.
putting them that clost to the intake valve wouldn't seem to help much - especially that big. Looks like a flow restriction to me (you would have to wonder why the manufacturer wouldn't do this if it were so great).
my favorite was when i pulled one out of the intake of a Turbocharged car...
lets see.... swirl the air, hit a turbine, no more swirl