Ok - this is my last go round on the 1.98 ata subject, since I think we are getting off topic here.
Again, I can't dispute that there isn't any direct documentation where we see some luftwaffe mechanic noting that so and so's 109 has been set to 1.98 ata. Given the state of the luftwaffe at the end of the war, it isn't surprising to me that a lot of gruppe level documents would be lost / destroyed as the units are being disbanded, destroyed, or retreating, and the type of documents we are talking about are about the last things most historians at the time would give a damn about, even if they avoided destruction as the units retreated.
The kurfurst site has the one document that shows that the LW high command did issue orders to boost to 1.98ata on March 20, '45 - I did a quick lookup on the JG27 and JG53, which Kurfurst cites as operational 109K units that received this order.
III. JG53, which had 109Ks, was operational until May 8, '45.
IV. JG53, also 109Ks, was operational until April 30, '45.
I. and III. JG27, also 109Ks, were operational until May 8, '45.
Given, these units would have been in a sorry state in March - April, '45 but unless they are given to ignoring orders from the high command, they were ordered to boost to 1.98, and they were flying sorties after that order was given. Did they obey the order? I don't know. Did they have C3 fuel to allow the birds to fly at 1.98 even if they wanted to? I don't know.
The 109 fans can't produce the volume of USAAF or RAF docs that show that plane type x flew at boost level y (aren't bureaucracies wonderful?), but given that we have an order issued to operational units, I think the inference that some 109s flew at 1.98 is a fair one.
For the game, all that 1.98 means is that the 109K would be climbing faster and would have better acceleration and a higher top speed. Frankly, having flown the thing quite a bit, the extra power is probably as dangerous to the pilot as it is to his target. More engine power in that airframe doesn't fix its flaws, and it is easy to turn the 190K into a lawn dart already.
Can we find other rides in the game where the boost, flight model, ord loadout, etc. could probably be adjusted and improved - sure. Does this mean that we shouldn't look to improve the 109s, I don't think so, but I'll leave off it here and start a 109 thread to pose my next questions.
EagleDNY
$.02