What Unknown said here is NOT true:
To let you in on a simple mod to turn your 750f 17 pounder to a 21/23 pounder
only change the older fuel pump the the latest fuel pump (simjet/ jetcat/ FTE)
all can work
The RAM 750F was controlled by the ECU sensing CP (Compressor Pressure). 1300 mb of pressure was full thrust (about 17 pounds). If you use a different pump (assuming one that is more efficient), all that will happen is that the ECU will reduce the voltage to the pump to keep max throttle at 1300 mb. You will not be putting out more thrust.
The way you do that is to operate the engine at 1400 mb max instead of 1300. That should give about 21 or 22 pounds. I ran one at 1400 for quite a while. Of coarse at a higher power level, the engine will not last as long. You need someone like Andy Low (the designer and builder of the old style RAM ECU) to reset the ECU to 1400 max. At 1400 you can use any pump that works.