IMO, the best thing you could give the Luftwaffe would be something to get the radial-engine 190s "back in the game" as far as the Late-war goes. Whether that takes the form of an A-5 with extra boost, A-6, A-7, a lighter A-8, or an A-9, all are interesting possibilities.
Dunno, I still have to be one tenth of what I used to be in this sim, yet I do pretty nice in the Fw190A8. The plane is "in the game" as long as you keep self-discipline, know when to dive away, and are able to pull some good defensive moves if the need arises. At very low levels it's got a decent acceleration that somehow compensates for it's low speed disadvantages. Between that, the rollrate, and that everyone discards the A8 as a pork 190, you usually are able to suprise more than one overconfident enemy. In fact I rate the A5 as a lesser ride than the A8: the A5 is nimbler, but the A8 has better punch and is 15mph faster on the deck, and that's one of the most important things in the MA.
Said that, I of course (

) don't have anything against improving the line. An "eastern front" A8 configuration (soviets captured quite a number of 190A8s with all non-essential equipment retired, weighing around 4000kg, that's some 700lbs less than the A8 we have in the game), or a BMW801F option (basically transforming ithe A8 into an A9 so why not going the short way and adding the A9 alltogether) for the model would be more than welcome and very nice additions.
For the Fw190A5 the C3 petrol injection system (1.58/1.65 ata) would be really nice. Almost 250 extra hp, 360mph on the deck and much better acceleration/climbrate at low levels

.
The thing with the 190A options we're talking about is that there's no reason why either of those configurations should be perked. The plane would still be difficult to master and never too much popular. The A9 option would be a real monster down low, with similar performances to those of the D9 under 15000 feet. But the D9 is not perked, so the A9 then in all fairness shouldn't be either. If you perk one question arises on why not the other...and that would lead to a domino effect (if the D9 is perked why not hte La-7, etc, you know what I mean). An hypotetical A5 with C3 injection would be a bit less hard to fly, but still would be a pretty average ride in the main arena. Perking those options because historic rarity is not an option either (both the A5 with C3 injection and the A9 were common during WW2) and the Ta152H is unperked anyway...
The problem I sense here is that probably a big can of worms would be opened if those loadouts are added, unless they are unperked. Maybe a lower ENY for planes which use those configurations would be a solution...but neither of them warrant a perk because exceptional performance nor because rarity...