Engine sound questions

[Cote Dazur]

What needs to be done to the sound file of a particular car to have the sound of the engine louder or quieter. I do not want to change the level in the sound adjustment of the game.
If that is not possible, what are the files that need to be replaced to get a different sound of the engine for that particular car.
I played with .AUD file, but nothing I do in it seems to alter the inside the cockpit engine sound volume.


Eventually got helped and end up using the .aud file ( renamed) from another car.