How much climb/acceleration did it lose?
How long does the overboost last? What is the climb rate on overboost and what is max speed down lower?
Also if custom WEP durations are being introduced, can we have a three minute WEP on the Spit V and a one minute WEP on the BF109F-4? IIRC those are the limits placed on those aircraft at the boost settings they have in AH2.