Thanks for your feedback :) There is very little I can do, I think, because this is what is happening behind the scenes:
- Either the game is pushing the train full throttle, and my mod is pushing the brakes, to simulate realism.
- Or I throttle the fuel-availability (to starve the train of fuel) - this has to be enabled in the mod-settings, because it would trigger "train out of fuel" notifications all the time, which I have to suppress, meaning you will never get fuel-warnings anymore...
In the first case the game is absolutely right to have the sound match that of an engine running at full blast. You might wonder, why the train-smoke is not at 100% in this case, but only the occasional puff - well, because I removed the default smoke animation too, and created my own.
In the second case, everything works as you want, it will have realistic audio, but your locomotive fuel will constantly appear/disappear a few times per second, and you'll never get an out-of-fuel warning.
I'm not sure there is a lot I can do here, except maybe making the locomotives silent, and create my own audio, but... think of all the 3rd party mod-support I'd have to consider... like electric trains, ships, etc. This work on this mod is already 90% about mod-interoperability, and I'd rather not open yet another can of worms by rolling my own audio :)