I am sad to say the tornado failed miserably on my explorer. 98 4.0 SOHC. I actually "lost" mpg with the tornado on. Pretest I was getting 20 mpg and after the tornado was installed, I could do no better than 17.5 mpg. Once removed, I was back up to 20 mpg. Go Figure. And yes the installation was checked,rechecked and rechecked again.
The good news is I placed the tornado on my wife's 2001 3.3 caravan. Her mileage went from 17.4 mpg to 22 mpg. 24 percent increase and holding. Moral of the story........One man's poison is another man's medicine......OK Confuscious I'm not!