The ECU controls everything in your car, namely the air/fuel ratio throughout the rpm band. Evening out the curve to avoid flat spots/spikes while accelerating through the powerband will allow your car to actually harness the fuel being burnt, instead of running rich (unburnt fuel).

As for at the wheels vs at the flywheel - hp numbers at the wheel are dyno'd numbers. Hp numbers at the flywheel are what magazines and dealerships present. Our car "has" 120 hp, but that's at the flywheel. Once that power is transferred through the drivetrain and actually turns the wheels, it's more like 103 hp.

 

Couldn't have said that better

 

wow i see now thx..