Swirling the air before it is mixed with any fuel is pie in the sky advertising Hype!

A throttle body spacer can only do one thing.... increase the post throttle body butterfly area before the intake valves (called the plenum) by the the total amount of square inches it adds.

As a proportion of the total plenum volume, the 1" thick spacer is only a very minute percentage. The net effect will be to increase or decrease the air flow dynamics, and the total plenum volume and maybe, increase OR decrease throttle response, and torque.

$15-$20 to experiment with OK ....but for $60 or more for a half pound hunk of aluminum with some holes in it? In my book they are mostly hype and snake oil... I pass.