I would much rather see some extra variants of the Ki-84 added to the game. Which, emergency materials versions aside, would mean a slight increase in performance across the board and the gift of choice for those with good taste

The external differences are very very minor but a different interior is required for some of the variants. Perhaps during the next 3d vamp?
However, given how competitive the Ki-84 is in Aces High already, and given it is the pooiest production version fielded, it would generate more whines that the Spitfires do right now.
