By turning in just the fuel screw to the point of no governer response you get around 150 or 155 cc per 1000 strokes. If you want to use the pump on the vehicle you also have to adjust other aspects such as transfer pump pressure, timing advance, low idle, high idle, ect... as they all have an effect on each other. 280 to 300 cc per 1000 strokes could be possible with the modification of other internal components but would be very time consuming to be able to get it to run very well for everyday use. Pushing a pump this far jeopordizes its life expectancy and is just not practical. The stock pumps flow around 83cc per 1000 strokes. Basically for every 1000 strokes of the plunger, per cylinder, it will put out 83 cc stock. Some people take a draw for 2000 strokes instead of 1000 to be more presice on the the amount of fuel pumped, and thats also why you might hear 300cc.