Modding default airfiles/engine performance

Hi guysI am working on some display software (avionics) and I need to make some modifications to the engine data, oil pressure, oil temp, N1/N2 values, etc. What is the best way to go about doing this with known data? Air Wrench? Maybe another program or just Notepad? Im trying to modify the default LJ45 (FS9 and FSX) so that their values mentioned above have a more realistic behavior compared to the real world values, as the avionics sofware Im working with has been programmed to react to the published real world values, but of course there's not been some discrepancies found with how the default LJ outputs those values.thanks for any help.