The tropical Spit V is generally considered the low point of the Spitfire in WW2. The basic Spit1/V just didn't adapt that well to tropicalization. Its not all to blame on the volkes filter either, (compare to the much cleaner installation on the Hurricane), as the tropical Spits nose was also enlarged for a larger glycol header tank. I think much of the same could be said for the P 40E, Kitttyhawk 1 as well. Its the low point of P 40 development as well. Its a thousand pounds heavier than a Tomahawk, barely faster with an air filter installed, with a pathetic rate of climb, all to get 6x.50 s in the wings that can't be fired under G , or they will jam.