See? You shouldn't go around innocently poking sticks into hornet's nests like that
What we have now is almost the same as what happened to Spitfires chasing pressurised Ju86's up to +42000ft, not Axis fighters vs American four engine bombers...
Real B17's could not go to 35k with a bombload like in AH, the engines and/or superchargers would break.
Currently, the LW fighters are a pain in the arse to use for intercepting B17's because:
Fw190A-8: Fuel modifier + short arena distances means by the time you get up there the B17 is long gone, and if you chase, you run low on fuel before you get there.
Bf109G-10: At altitudes over 20k, it won't fly level without constant right stick being held. Plus the fuel situation again.
The Macchi isn't much better than it's German counterparts, since with its DB605A, it's ceiling is ~37k? It sucks over 30k - I shot at a B17 at 35k and I stalled
But, the Spitfire rightfully should be the best interceptor at high alt, except maybe if we had GM-1 for the 109