My rF2 install was just updated with the latest fixes, also on the BTCC cars and when starting a race I noticed engine sound levels were very low and some engine/turbo and transmission sounds seemed to be missing. Increasing volume settings (most of them are already at 100) did not help. CrewChief sound levels are normal, so my systems sound level settings were ok. After starting up rF2 again the sound seemed to be back at normal levels. I had this problem before already also on RC builds. I think it should not be necessary to restart rF2 after updates to make the sounds work properly? I have sound set to 255 channels, so that should not be the issue.