you mean that piece of metal that just spins and tumbles the air? i´m skeptical because all the people on tv that said their gas mileage improved never bothered to show any gas receipts. I think it just interfere´s and chokes the intake, but I haven´t had any personal experience with that particular product. if it wasn´t $75 I´d buy one, just to try it.
tornado air filters dont do much, but if u added a thingy to swirl the air before it went into the engine, thats good cus it mixes with the fuel much better and it spreads all over the chamber instead of in one generalized spot.