You can make engines quieter by decreasing the max and min inputs, although that also affects the performance of the engines.

Unfortunately not. :(
What you could do though is drown the sounds out with other sounds, like, you could have loads of low input jet engines to make a low rumbling noise or whatever you want

@Aeromen ah dang.. I got actually working props on this and I obviously used small plane engines and I wanted to turn their sound off and I tried with overload and it didn’t work.