ORIGINAL: Charlie P.
Worst part about FMS is that most of the WWI bipes seem to be electric and without . . . enthusiasm or charisma.
I think you can pretty easily give a FMS model a new sound.
The sounds (in FMS Beta 7 anyway) are .wav files in the 'Program Files\FMS\Model' folder. Pick one that has a nice sound, make a spare copy and rename it to match the model you want. For example, I took the 'CurtissR3C.wav' file and renamed it 'Su-26.wav' to give the Sukhoi a throaty sound.