I would be interested to know if MK operste a mix of engine types. Several years ago a major airline operated a mix of P&W powered 747-100s and RR powered 747-200s. Because of the different situation of the probes, the max EPR on the -100 was 1.44 and the max EPR on the -200 was 1.63. On a max power take-off from Miami, the engineer, who had been predominently flying the -200, set 1.63 instead of 1.44. The aircraft performed very well but they didn't use the engines again. Do it the other way round and you might not use the plane again.
Airclues