One issue I have with the J2m is I have absolutely no information on it. From what I know it was an interceptor, that sacrificed maneuverability for speed/climb rate and was designed to shoot down buffs, however what I am puzzled at is most information gives says it did not have a turbocharger.
Basically its an early model P40 with 4x 20mms and uses boom and zoom tactics to hit buffs, but I do recall very few were ever made.
Only thing I do recall is they were introduced in late 1944 in small numbers, but it gives no information exactly where.