Well every comment has been helpful so far
The problem is that the custom music isn't added in the MT intro itself. It's the music that's being played in the background of the track the whole time. Meaning I can't shift the track in the MT a few milliseconds because it's not their.
If you want to add custom music for the track and custom sounds for the MT intro, ingame and outro both audio files will be played simultaneous. The custom music plays constantly in the background and you can't (or I haven't found the feature) dim/silence the background music at designated points. If I want custom music playing throughout the track non stop I will add a song through the custom music function, but if I want the custom music
and a custom sound file that is for instance a song to be synced with the intro, I can't because they will be playing together and not perfectly in sync. This will probably result in a mish mash of sounds and won't be pretty.
Maybe I can try to add the song as a custom sound, in the ingame MT, triggered throughout the whole track. But I have my doubts about it. The custom music keeps on playing without skipping in the background even when you crash and have to restart the track from the start. I think if you have the song triggered as a sound in a trigger at the start you might hear weird stops and starts (skipping) of playing the song. When playing the track over and over again you will only have heard the first part of the song. Compared to custom music where you will hear the complete song even when restarting the track. (without exiting the track of course)
Is my thinking process wrong or am I correct? I don't know I'm speaking from my own experience with the game. And I haven't tried everything I have said.
I still like your idea and might try it out!
Thanks for the comment it is of course much appreciated that your bring your thoughts about this.
This way we all learn more