They have GOT to bring back Pearl Harbor
Paradox has GOT to bring back Pearl Harbor. Before, the loss of 8 battleships was a serious blow to the US, and a defining shape to the Pacific war. Reynold's The Fast Carriers shows this, if in exhaustible fashion. King and Nimitz had to basically construct modern carrier doctrine out of whole cloth on the fly, because carriers were the only thing they had to fight with. Though, I would appreciate a project to, over the course of a year or two, trade a few civilian factories to repair those sunk battleships, as was historically appropriate.
As is, having a bunch of battleships wandering around means I can, like I just did, mollywhomp a trio of Japanese heavy cruisers and a bunch of tin cans, which is a significant impact to the war.