We should be getting the 1943 and 1944 versions of the Spit 9 and Spit 14, respectively.
The ones we have now are under-powered, and have no reason for the ENY to be so low. There's just no excuse for the 14 to be perked, since it's so under-powered compared to the mainstay 14, which had (I believe) +25 boost.
And our F4U-4 shouldn't be perked at all. It has only slightly better performance than the P-51D (although it's a pain at low speed/low alt), and it doesn't even have cannons.
The solution? We should get an F4U-4C sometime in the future. It was the F4U-4, but with 4x20mm cannons. Oh, and it should definately be perked.