You guys seem like a broken record... how about starting another Spit XIV thread so we can see another 100 "Is so!" "Is not!" responses.
For what it is worth, most of the other Perk planes mentioned here (P-47M, Ta152, P-51H, Me-262, etc) are 40-50 IAS faster than the XIV at altitude and can handily outdive the XIV at any alt.
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SnakeEyes
o-o-o-
=4th Fighter Group=