If you have the PC version, you can try them out. Some people found the files packed among the game files, and are working to get them all up and running.
Makes a huge difference, and isn't all that much more taxing either. Begs the question why Ubisoft didn't bother including them as an option.
http://www.neogaf.com/forum/showthread.php?t=838538
Modder "The Worse" originally found the files.
You're Gonna Carry That Weight.
Xbox One - PS4 - Wii U - PC