Copy the XNFSMusicPlayer.asi and associated files into your NFS Carbon directory.
Unlike modern games that may use standard .mp3 or .wav files, NFS Carbon stores its music in the SOUND\PFDATA directory. The primary files involved are: nfs carbon music replacer
Use an audio editor to ensure all your replacement tracks are roughly the same volume so one song isn't blasting while the next is silent. Copy the XNFSMusicPlayer
A plugin that overrides the default in-game jukebox settings. nfs carbon music replacer
This happens if your custom audio file size is drastically larger than the original track, or if the sample rate is not exactly 44100 Hz. Re-encode the file with a lower bitrate.