The vanilla version of Black Flag on Xbox 360 suffers from screen tearing and pop-in. The Jtag/RGH scene highly values , which patches the engine to run smoother. Because you are not connecting to Xbox Live, you can install TU3 manually without worrying about a console ban.
DLC for JTAG/RGH consoles requires specific folder structures on the internal hard drive (HDD1) to be recognized by the game. 1. File Structure & Path Assassin-s Creed 4 Black Flag -Jtag Rgh DLC-
(Standalone Story DLC)