I know that you need to improve the breathing of the engine by fitting a larger turbo/different camshafts/porting the head/etc. to make use of the higher flowing injectors. And that your chip must match the total engine configuration. But that is not my question. I just want to know to which power levels the different injectors are sufficient.

If the power scales linearly with the injector flowrate I would expect that Siemens 55s would be good for about 520 bhp, Siemens 72s would be good for 680 bhp and Siemens 83s would be good for 780 bhp. But I have the feeling these numbers are very high so the real numbers are probably a bit lower. But how much are they?