Change the permission of package info on system app

I am trying to change the sound of the PowerChime.app(/System/Library/CoreServices), when i plug in the charging cable. That means that i need to swap out the /Contents/Resources/connect_power.aif. but I do not have permission to. I have tried sudo chmod 777 / and sudo chown [user] Resources, that gives me a Operation not permitted. What can i do?