Will this pack replace my current songs?
No

Where are these songs sourced from?
Already done game audio rips and album rips.

Are these high quality?
Yes and no. 2 games have flac sources but the game doesn't support them and takes a bit of space up for most users. Mp3s in this pack average from about 128kbps to 250kbps.

Couldn't I just add songs to my game myself?
Yes you could, but it takes time.

How are the songs organized?
Main menu songs and under-1min songs play during the main menu.
Slow pace songs play in the garage.
Hard and fast songs play during free roam, drags and races.

Would this music pack sound fit well with the current in-game music?
Yes it would surprisingly. The in-game music and this music pack have the same genres.

Can you add music from NFS:MW and above to this pack?
Probably not. Those games have songs that play during the main menu and races. To me its weird having the same songs play in the menus and races. Also its a waste of space.

Can you do gran turismo soundtracks in a different pack?
I was thinking about. GT 1-4 can fit nice in 1 pack but GT5 and GT6 would have to be separate.

I have music playing problems:
Delete music folder, reinstall music pack. At worst, fresh reinstall of game.