Both Fortnite theme song  (old and new one ) . installation can be found in readme.txt in the mod folder!

I don't care if this idea was done by any others people. Clear?

There was a error uploading the file thourgh modworkshop servers, so i uploaded this thourgh mediafire!

REQUIRE SUPERBLT AND BEARDLIB! 

Copy from the readme.txt : 
Copy and paste both folders into steamapps\common\PAYDAY 2\assets\mod_overrides
If you dont have, just create one!

Then join the game, from main menu, go to options, sounds and choose custom menu playlist, tick both old and new fortnite
main menu ( if the game didn't) then go to custom menu tracks then press the first one ( main menu screen ) scroll to the 
bottom and choose 1 of them! Done! It's installed!

CREDIT TO EPIC FOR CREATING BOTH OF THESE BEAUTIFUL THEME!