I was spetical and searched the net and all the negative comments I saw came from people who did not even own one. Since I read some old posts here that 2 people reported some good improvement so I gave it a try.

Tornado Air works for me. I saw 0.5mpg improvement after installation and battery re-disconnect. Now I'm getting 380 miles per tank on 21 gallon fill up (18mpg). Was getting 17.5mpg before tornado. Mobile 1 synthetic gear/atx/engine fluid helped it from stock 16mpg to 17.5mpg.

Only mod I have is K&N cone filter. Power mode all the time.

Planning on getting a good muffler but not sure which one..