So cause I felt like it, I just compressed the game again (only images), to 97% quality webps. In the end the file size came down to 4,53 GB instead of the orig 5,74 GB. So not that much saved. Also need to add that every different format will make the game looks different even just slightly (For example compressions to webp will make dark scenes look pretty bad).
And the game has exactly 13.040 images.
It's a pretty good compression already imo.
But then again.
EchoFoxtrot No converting the images next release! Use the pngs DAZ spits at you after rendering.

Shit would be hilarious