Note: You must have ScriptHook V and OpenIV installed, including the OpenIV.asi script.

You can get them from here:

http://www.dev-c.com/gtav/scripthookv/
http://openiv.com/

This 'mod' replaces all the 'interactive music' (ie. the 'score', or the mission soundtrack / background music) with silent .wav files. It's simple but effective, increasing immersion in the game tenfold. So far no side-effects have been discovered (and it does not affect the radio music), but I still suggest you make a backup of your INTERACTIVE_MUSIC.rpf before installing in case of corruption (or in case you want to play online - remember to always play online using a vanilla copy of GTA V, or else you will be auto-banned!).

Enjoy.

Regards,
Zenarchist.