N1K is a very good fighter Under 10k with a sweet spot at around 5k. It's only real weakness at that alt is its Top speed(Its dive characteristics are pretty good compared to most other Jap fighters). However once the N1K is above 10k, the F4U actaully out climbs it.
The N1K and La7 seems so uber because they are mostly optimized for low level, once they get to the medium and high alt ranges they'll get chewed up.
The Spit16 is a different matter, it holds its amazing performance throughout its Alt range, but it is slower than the average super late war fighter. Iv'e always been confused to why it isn't perked, but I guess its range, lack of out ride speed, and poor attack ability(although not really) are why it doesn't get a perk price.
