Their rate flow rate at constant pressure is linear. If you increase the size of the injectors by x percent they will flow x percent more fuel than the injectors they replaced "at the same fuel pressure".
Fuel flow changes at the square root of the fuel rail pressure change so if you also modify the fuel pressure you will have to make that correction too.
For the same injector pulse width your new 600cc injectors will flow 1.81x the fuel that the old injectors did, once you get engine rpm up a bit.
There is a slight chance that this will not hold at low rpm due to changes in dead time for the injectors.
Once you make the initial correction at idle the new larger injectors will be using very short pulse widths. It takes a finite amount of time for an injector to open once it sees an injection pulse, so if that pulse width at idle is short compared to that dead time for them to respond, they may not have time to fully open up, and you will have to either increase the pulse width at idle or if your injection system has the means make adjustments for the dead time of the newer injectors. That lag in injector opening is called different things by different engine management systems but look through your docs for the Power Commander and see if they mention such a setting.
You might have to go to an injector company like RC engineering to find out the dead time for the new and old injectors if you cannot find it published on the web.
Larry
