I really love that we can add our own custom music into the game, but I have some small issues:
-Custom music tracks prevent vanilla music tracks from playing or the chance is really low (played 10 times only got custom music tracks)
-I'm not sure but I think the quality of the custom music tracks is worse when played by the game (i used mp3 files)
Another thing which is not really a bug but I'd like to see changed is that when racing It'd be nice if a different music track would be played after the previous one to avoid the music getting repetitive when you have lots of laps in the race.