http://www.axisandallies.org/forums/index.php?topic=26960.0
it is right below this topic (3 spaces down or something). USA economy just goes up by 23 a round sooner (but he lost dd and sub to kill nothing and that has to get reinvested, also the fighter but that kills a couple inf on average, he has to reinvest something into the pacific or he can just let japan win).
Anyway Japan in J1 DOW as far as income goes, makes the same amount as not going to war, but steals borneo and kwangtung from uk pac and phil from usa. Picks up free kills.
I am more concerned about usa buying 4 bombers, moving fighter to iceland, uk1 inf and minor complex on egypt, knowing usa will guard him in the event of sea lion g3… germany can always do a  g4 takeover of london if you really want to take london. Usually germany goes barb anyway.