I installed the rapid force exhaust system in MY 2010 FJ AT with stock tires and rims. I now get 22mpg city and 24mpg hiway. This is a 2-4 mpg increase over what I got with the stock exhaust. It is not snake oil, this actually works. when I had mud tires and steelies I got 17mpg -20mpg. It took about 4 tanks of gas to stabilize. If any one is interested I can post a picture of it installed.