Welcome to the club David.
If you could get the intake air spinning as it enter the cylinders, or at at least on the leading side of the intake valves, then yes that would help to atomize the fuel into smaller droplets, spread the mix better in the cylinders & enhance combustion & total burning of the fuel, which would improve mpg, but the tornados are installed so far upstream from the actual air entry into the cylinders, that the air has straighteded back out to normal path by the time/distance, so there is no positive benefit to them. The Japanese motorcycle manufactures spent millions of $$$ on R&D on their 4 valve heads & twin swirl combustion chambers to perfect this rotational movement, but the Tornado doesn't sucessfully do this.
Your friend that actually showed a gain from one, probably inadvertantly fixed something else while installing his since he showed some positive results. Maybe he moved a plug wire that was arcing, or cured a vacuum leak, pumped up his tires etc. Now that he's showed some mpg gain, I'll bet that if he took the Tornado out he would still be showing the same mpg gain without it.
