Please reread my post that you refer to. I didn't say all planes had of WEP. I said that most planes did. This is a true statement, most planes were only rated for 5 minutes of emergency power. The part about being fairly generic had to do with what happens when when that limit is exceeded.
Looking back the WEP thread, here is Pyro's response:
WEP duration is treated fairly generically for gameplay purposes. Most planes were only rated for 5 minutes or so, but that doesn't necessarily mean their engines couldn't handle longer periods.<snip>
The differences between emergency power and other systems like water injection are modeled.The first sentence gave me an impression that there will be only minor differences between planes regarding WEP. And because word 'gameplay' comes up in context, I might have drawn some hasty conclusions which might be incorrect. I certainly hope so

The last sentence, on the other hand, is pretty clear and just what I (and many others) wanted to hear!
To set the records straight with everybody, I'm not seeking edge for myself by posting here. I don't want to see any plane to be too good or too bad, I want them to perform just the way they did in real life. I want to relive those events some fine individuals lived 60 year ago. I might appear biased because most of my little knowledge is about Luftwaffe planes and I usually don't want to write about things that I'm not fairly sure.
As for tweaking FM's in WB for playability, I have hard time to believe it was done. I believe more in theory of inconclusive data and difficulty of plane modeling. To get all performance areas accurate must be enormous task. If the FM engine is not sophisticated enough, compromises are inevitable.
Ps. beaz, I agree with your post completely! But I'm afraid we will not see any practical way to limit plane numbers in general arena.
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Obfr. jochen 'Stern von Afrika' 2./ Jagdgeschwader 27 'Afrika'