404 Override Not Working

What you need todo is create your own show_404 method or redirect to your custom Notfound controller instead of calling show_404 and pass along any needed arguments

Is this not what extending the core CI_Exceptions class is achieving? ok it's not a separate function, it's extending the core instead to get the same end result but i don't see how this is a bad solution just because it's not the one you would personally go with?

Please can you explain to me why it's a bad / incorrect solution?