1) An increase in torque for a better acceleration and hill climbing ability.

2) An increase in power particularly at slow running, producing quicker throttleresponse and improved driveability.

3) A fuel reduction that can be obtained by accurately gauging the stoichiometric ratio, i.e. the air/fuel ratio

4) A reduction in emissions of Co2, Nox, HC, for preserving the health of our environment.

That is to say:

+ ACCELERATION + POWER - FUEL CONSUMPTION -TOXIC EMISSIONS

But remember... always keep an eye on the road, drive safe and avoid taking parti in dangerous and useless competitions unless you are running on track.