here's a list that (i hope) shows which track id was replaced with which song
here's for hoping i'm not pulling some names out of my ass
tracks in bold aren't from Y3,Y4 or Y5

0538 - Get Over It - y4 material delights
0542 - Amon - y5 maximum ill luck
0545 - Receive You The Madtype - y5 and slash you
0546 - Receive You The Prototype - Receive You Reborn
0281 - Flirt with Bomb - y4 the myth
0282 - End of the Dogma - rebellions y4
0209 - Unrest 2 - y4 nervousness
0544 - The Wicked - end of rematch y5
0594 - For Whose Sake (no intro) - y5 battle for the dream
0208 - Unrest 1 - y4 whiskey and rhapsody
0582 - lau ka long - y5 leo the aristocrat
0595 - disco place - funktastic hit y5 (ultimate battle)
0537 - funk goes on - isolated fight
0543 - vertical point - y5 full scale offensive
0386 - vertical point - y3 end point
0536 - ruthless octagon(coliseum finale) - y5 extermination
0540 - scarlet scar - y3 tamashiro family
0535 - amusing octagon - y3 ryukyu humming


Installation (requires RyuModManager by Sutando Tsukai 181):

• Locate the folder where you've got Yakuza Kiwami installed (use google to find game path depending on the platform you got the game from)
• open or create a mods folder inside the data folder and drop the musicmod folder from the archive in there
• add new entry to ModLoadOrder.txt called musicmod
• open the RyuModManager executable to load the mod
• gaming
  

you can also install it manually by going into soundcpk and backing up the bgm.cpk in there and then adding the modded bgm.cpk in there

I've also uploaded the hca files I used for this mod so that other people don't have to download 1.4 gb for just a few changed tracks. You're free to use as you see fit in your own mods as well, refer to the list above to see what id represents which track. You just have to figure out how to repack the tracks again (it's not too hard)