J2M2-J2M5 had maximum flap deflection of 50 degrees, but for combat it was 16 degrees.
Source : Model Art Issue 470 - Page 104 or Famous Airplanes of the World 061 - Mitsubishi Navy Interceptor (J2M) Raiden (Jack) - Page 14
Ki-43 had maximum flap deflection to 30 degrees with speed limit of 250 km/h , and combat deflection 15 degrees with speed limit of 400 km/h.
According to the source :
"6. The butterfly flaps were adopted to increase the performance in banking (turns). The performance is increased considerably by lowering the flaps 15 degrees. However, continuous use will create drag. The flaps operations in combat (Up-Down) are controlled by the flap selector control lever, or, electrically, by the control stick push buttons."
Source: References on piloting Type I Fighter, Model 2 issued on January 16th, 1943 by Army Air Inspection Dept, Akeno Army Flying School.
Ki-44 had maximum deflection of 35 degrees with speed limit of 250 km/h, 15 degrees for combat with speed limit of 400 km/h and 9 degrees up to 450 km/h.
Source is Ki-44 manual, but I dont have exact title translation.
N1K1 had a two stage flaps, to be precise it had a "master" flaps of fowler type which could be deflected up to 19 degrees and at the end of those there were "slave" flaps of standard split type which increased the overall deflection to 41 degrees. If I will find a picture, I can upload it if need be.
The performance of those was a decrease of turn radius by 20 % or even more, however the turn time did not improve as good as turn radius and usual turn time decreased by about 1 to 1.5 second.
The maximum lift-coefficient are approximetely as follows:
Aerial-combat flap at 0 degrees 1.7
Aerial-combat flap at 19 degrees 2.5
Source: Aviation report 0311 - Study of aerial-combat flap (Part 1), Model 15 prototype float seaplane fighter - issued in 1943.