Grumman F8F Bearcat is the United States Navy's final reciprocating/piston engined fighter aircraft. Unsatisfied in spite of the Hellcat's satisfactory military gains, this craft designed to annihilate the Zero fighters was reconstructed by American design after completely dissecting a captured Zero, and is thus known as "a half-sibling of the Zero fighter." (Various different opinions exist regarding this.) Smaller than the Zero, its about 10m long fuselage was equipped with a 2100hp engine. It also carried four 20mm cannons, which meant it had substantial firepower. Its climbing power, descent speed and maneuverability were all top class, and it can be imagined that if this aircraft and the Skyraider had been in time for WWII, Japan would not have got away with just the degree of damage it actually did. However, its biggest weakness was its lack of flexibility, which meant it could only be used in limited air-to-air combat missions. This was due to the fact that such a high-power engine was forced onto such a small-sized fuselage. Due to its late development period, it was overpowered by the jet fighter aircraft, and was thus an aircraft that was unable to achieve satisfactory active participation, but even today it is used in air racing.
Other opinions: It is said that the design concept of "the combination of small craft and high-powered engine" of the Fw 190 captured by the Royal Air Force had a large influence on the F8F.
I believe a modified racing F8F holds the current speed record for a propeller driven aircraft. Even if I'm not correct there, it's an exceptionally fast aircraft.