I don't have OA, neither CO, just the Original A2, It won't work for me? because I tried, It told me that if I want to install ACE I need CBA, I downloaded and install the both, it looks like ACE working, it gives me the Main Menu Icon and Log, but it doesn't take effect when you play, You can't use the Menu that helps you use items and stuff, you don't get deaf when heavily shooting and etc...