If you wish to remove breathing audio from other characters too, you can do exactly the same as with "breathing_michael_01.awc" file. For example in "Trevor" folder you can find the .awc file
that you will replace the original file with in the "PAIN.rpf" folder in OpenIV. Also you can find .oac file with .wav files in "Other Files" folder and of course a backup file in "Backup"
folder. I've also included "Test", which I found to be breathing files also, but I don't really know for which character these sounds are, so I just included them too.