By filling the crank it smooths out the staged idle effect right now think of what it takes to do this , a more direct route for the incoming fuel/air to get the intake ports .

So now you've created a more direct path there is less turbulence causing cavities in the path which makes a more direct throttle feel which also makes a more instant engine decel and a better clutch disengagement allowing the car to roll through corners better and allowing you to use a lower stall clutch which results in better overall mileage


As far as on throttle difference between filled/drilled unfilled I have noticed a more instant throttle reponse and a more punchy yet smooth/direct throttling


These are things I have noticed


I thought you were running non novarossi engines these days ?