[8FS_Bulau]

I think you may be mistaken about what Oleg was saying. Correct me if I'm wrong, but, one of the first mod activators made here was called "English Sound Mod", and all it did was put cockpits to most of the AI-only planes, and add new sounds:

(The link is inoperative)

AFAIK, there is no way to change the sounds without a mod activator, except for playing around with whatever files you can find in the samples folder. All the presets and engine sound samples are locked into the .SFS files.