whats the difference between
--alt-preset extreme -Z and --alt-preset extreme if there is any
i only saw the one without the set before does it change anything?

Try to encode one wav with --alt-preset extreme -Z and --alt-preset extreme... and add --verbose to both. Then you will see the most substantial difference; the bitrate is a bit higher with -Z parameter than without it. On some critical samples gives -Z better results... But here at HA are more competent people who give you better explanations.

I believe it forces a different noise shaping model. At least I think that's what I read from CiTay.