The tornado is nothing but snake oil and has been for many years. Don't be fooled as fuel injected engines are not the same as water in a bottle. They do something for carburatored engines but not for fuel injected engines.
Now K&N type air filters are a different story, and are used in racing engines. I used one for a year in my Insight, but didn't notice any improvements in fuel mileage in it. I think it's just that Honda did a very good job of getting the most mileage out of the car.
I had a K&N air filter fitted at the last (36,000 mile) service. It has made the acceleration above 2,500 revs. (when the valve lift and timing alter) noticeably better without having any detrimental effect on fuel consumption, provided that one does not then proceed to play "boy racers", e.g. blow off BMW`s by using second gear/full throttle up to 69 mph! Incidentally, the lifetime fuel mileage is 70.0 mpg; that is, English gallons, not U.S.