[ecomodded]

I suspect the leaning out of the mixture will raise the exhaust temperatures significantly.
I would use less throttle in your daily driving and more coasting, you will see a 5 mpg increase, without toasting your motor, like Daox suggested you would.

Not long ago i was thinking on restricting the actual airflow to de-tune the motor to make less horsepower.
What i had to do was tune my driving habits not de-tune the car.