Do the simple exercise of making a paper graph of the Hurricane I, using Kwiatek's charts and B6's data (in game now) ... the actual game has +60 km/h more at 5000 m than Kwiatek's 12 lbs Hurricane I, and +105 kmh at 6000 m, with a comfortable +25 kmh at 4000 m.
No red pilots complained a lot about it, iirc ...
On the other hand I agree that the 12 lbs boost / 100 octane fuel must be modeled, of course with a limitation on overheating and engine life as in RL, to correct the Hurricane I performance below 3000 m which looks excessively penalized,
IF KWIATEK CHARTS ARE ACCURATE
Cheers!
Ins