In Japan it is believed that the following description
Rated Shiden Kai (from japanese wiki translated by google)
Was developed concurrently with Kai Shiden fighter expression of four Nakajima Aircraft equipped with the mover as "Gale" (hereinafter abbreviated as against formula IV) and, when compared on the catalog specs a maximum speed of Kai Shiden, streetcar more inferior breaks. Maximum speed of 335 knots during trial breaks Shiden (620.4km / h). Horizontal 348 knots at full speed (644km / h), respectively. 624 ~ 640km / h top speed of the initial prototype four-wire, four-wire prototype that was later converted into a single exhaust pipe further thrust equation, so fast 10 ~ 15km / h from the initial prototype. Dated January 1945, "Pilot Reference Kai Shiden attitude 'as seen from the descriptions of twelve types of honor is a mover and Shiden Kai Shiden about 10% lower than the state rated output limit for driving respectively.
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"The Illustrated Directory of Fighters" (Author Mike Spick) according to P.218, N1K2-J (Kai Shiden) is 19,030 ft (5,800 m) 416 Maximum speed in miles (669km / h), 358 top speed at sea level miles (576km / h), the rate of increase is 20,014 feet (6,100 m) that contains six seconds and a 6-minute performance. Although these figures are covered with figures and comments are based on test data with aircraft that were captured by coalition forces, including more sources of information from which the test is unknown.