[ACE-OF-ACES]

I can give you two just off the top of my head.

Clapped out Hurricane MkI's refitted for service late in BoB had substantially lower performance than factory fresh examples, in some cases as low as 305mph top speed.

Late in the P40's service life, many Allison engined models were modified in the field to run at 72" boost with a re-geared supercharger, giving an output of just over 1500hp at sea level, substantially boosting the P40's low level speed but exacerbating the power problems higher up.

That would fall into the catogory of "Unless some authorized or un-authorized filed mod was implemented that change the factory settings"

Not usually, although a well maintained aircraft with the engine run in and a polished paint scheme could well be a bit faster than "factory fresh".

Well I see engine run in and break in period to be one in the same

As far as polishing and or waxing of the skin

That would fall into the catogory of "Unless some authorized or un-authorized filed mod was implemented that change the factory settings"

But I think we would all agree that would help

But I don't think it would qualify as 'vastly different'

This is my understanding too, hence my question to Fireskull about why he is putting forward the idea that throughout the war front line service Bf109s retained a superiority in speed and climb over frontline service Spitfires, when a direct comparison of factory spec aircraft shows this should not be so.

Ok good so we both agree they can only degrade with time

Unless some field mod that changes the factory settings

Oleg Maddox seems to be attempting this with Storm of War, in that planes with be factory fresh when new and degrade with use in missions. The effect will be simulated both visually and with a loss of performance and reliability.

Interesting for offline play

But I doubt it will factor into online play