Rockstar always rolls them out dialed waaaaaay back. Up until GTA V had already been out for a year the mods were still being applied to IV. They had 4K working in that quite a ways back. I still see a lot of blurring, and the people don’t appear to be optimized but it looks damn good. Here was IV Redux, assuming same author: http://www.moddb.com/mods/grand-theft-auto-iv-redux (warning: autoplay)