Replacing Music in NFS HS
First you need to download a music converter to .ASF format.
You can put it anywhere you want. Then launch it, select a music file (MP3 or WAV, and this music MUST be at 22050 HZ), select the folder where the converted music will be saved and click Import.
But the resulting file cannot be put into the game, because NFS 4 has old methods of music playback (because of this, such music sounds like a collection of noise).
You download this program.
It completes the music conversion. Create a BAT file, write in it (the BAT file must be in the folder with that program):
splt2int.exe .asf .asf
After that, the resulting file can be used to replace any track from the game (after renaming it, of course).
P.S. During races, some music sounds quiet.