The Rainbow is indeed a most interesting aircraft, but I think the Tempest II is a good example of proper attention to engine installation drag. It was faster than the F8F with minimal increase in power with 24 % larger wing plus heavier airframe. Another good example is the La-7.
Another good comparison: Tempest II vs. any model of the P-47 at sea level. Closely similar wing areas, yet with settings giving similar power, the former is very much faster.