I installed the Tornado thing in the gas tank, one on the transmission, and one in the trunk on the spare tire.
Then I installed a K-M air filter that worked so well, I stuffed 3 more under the hood and taped them all together.
I bought a $1,000 device that turns ordinary water into helium, which pumps directly into the fuel injectors and has an attachment to fill balloons as well (a sideline business).
I then over-inflated my tires to 185 psi in the rears and 190 in the front tire ( I took one front tire off to save friction and I simply lean to the left to compensate - works great most of the time)
Before these mods I was getting 21.7 mpg with all city driving but now I'm up to almost 24 mpg with all highway driving.
Quite an improvement for a small investment, and the balloon business has really taken off, I forgot my anniversary and instead of getting the bit*hin I normally would have, I simply inflated a dozen party balloons, tied em up, and all was well.
The only downside is that I pretty much have to drive all highway miles now as the car drops onto the brake rotor if I come to a quick stop. Parking it is also more difficult.
It's all worth it for the extra mpg's !