This. Ever since I've started making music and sound mods on other games, I've always had a blast doing it.
Very coincidentally though, I also made Kingdom Hearts based ones (big fan) and used the 13th Struggle as one of the PvP (group) themes in Dragon Nest. Not to mention, KH3D's version of Traverse Town music was also my song choice for Kokkara in the current DBO mod I'm making, wow. Might change it though, not sure. (it's not a full Kingdom Hearts mod too, as you might have noticed from the other thread, don't worry.)
That's because sound.pak is just the header used to open what's inside all the other sound paks (just look at the file size, of course there are no new sounds there). All of those files are the ones that have to be uploaded, but they round up to 1.2GB in their original state, all together.
Also, needless to say that installing the mod this way will only let it work until the next game patch, and also might cause your game to crash and stop working if you don't switch back to your backed up original files, just like the old english patch used to do. Just a friendly warning.