I guess it's possible that you could get a mpg or two if you are still running the stock airbox. It causes the air to the motor to spin, kind of like a tornado. This would probably not be useful if you are not on the stock airbox and intake, because most aftermarket intakes flow more air more efficiently that the stock one.
The principal the tornado works on is that the air going to the motor has pockets in it (of air...?). By spinning the air, the theory is that those air pockets will be removed, thereby allowing more air into the engine.
The tornado does not force anything extra into the engine, if that's what you're hoping. It just streamlines the air travelling through your intake. I doubt there is any real benefit, other than a tornado sticker to put on your car.
you are lucky, if it were up to me, people that posted these questions would get a 1 week temp ban
do you really think you are the first person to ask this question, since this board has been around for 4 years. search on my user name and the word retarded to see how many other times it has been asked
use this feature for any beginner_basic questions you may have from now on