Who said anything about perking it? Unless you know another 25 ENY plane that is perked. Most of the planes with a K/D greater than 1.0 are not 40 ENY birds. Sometimes the C.202 does well in that regard, but it is only due to one or a few good pilots (and hardly anybody else) flying it. The Ki-43 has a very respectable K/D for being a lowly 40 ENY death trap that gets a fair amount of use. Even a hopelessly mediocre pilot that I know quite well has a record of 28 kills to 2 deaths .vs fighters, flying the Ki-43.
The A6M5 is 20 ENY and it does carry ords and have better guns, yet it doesn't take damage as well (which is kind of strange) and gets it's tail feathers handed to it by the Ki-43.