Spitfire's, as well as P51, N1K and other rides with a lot of usage are far from being #1 in K/D ratios.
Undisputed #1 is Tempest , followed by usual suspects like 262, 163, F4U-C and -4, Hurricane II, Typhoon, 109K.
First Spit's usually to be found > rank # 20, with La7 & N1K not being that much better.