Militarist Japan's airplanes were often handicapped throughout the war by the lack of efficient turbochargers and turbosuperchargers. This is not to say that none of the Japanese aircraft had turbochargers or superchargers, as some did. Nevertheless, there were quite a number of Japanese designed that were intended to have turbochargers (e.g. the Raiden interceptor), yet continued to lack them during the war, often due to the lack of sufficient high-temperature alloys.
My question, then, has two parts:
1.) What is the best turbocharger or turbosupercharger, fitted to an airplane, that can be convincingly sold to Militarist Japan before the outbreak of war, or captured by them during the first phase of the war?
2.) What is the effect on the war if Militarist Japan is able to fit these devices to those airframes which were intended to have them, but never did in OTL?