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Is there a way to lower the volume of a specific sound effect? Particularly I would like to make the car's noisy engine quieter, as I find it much too loud in comparison to the global sound effect volume.
If you want to adjust exactly one sound then you have to make a mod yourself. If you're fine with adjusting all car sounds (gun, etc) then you could use my mod Eradicator's Safety Ear Muffs. You can add "car" (lower case, no quotes) to the startup mod settings.