The power torque and horse power is very noticeable. The stock setting seems to add about an average of 6 mpg if drove at 60 mph, also with slow take off from a dead stop. Those averages go down slightly as I go through the spot and spot plus. Now as for the race setting, very powerful and noticeable from stock setting. Fuel mileage goes down to about 19 mpg. However, speed gain is very quick.