[...]In September 1944 an equipment kit was installed which raised boost pressure and increased the Jumo 213 A's emergency output from 1,750 to 1,900 h.p. The installation was carried out on-site by Junker's Tecnical Field Service (TAM). This increased emergency power could be used at altitudes to 5000 meters. At the same time, use of takeoff power (1,750 h.p.) was extended to 30 min., while authorization was given to use combat power (1,620 h.p.) without restriction.

The Junkers technical field service visited III./JG 54 monthly. In October the number of Fw 190 D-9s on strength with the Gruppe rose to 68. Of these, 53 had been converted to 1,900 h.p. and one was delivered by Focke-Wulf with the MW 50 system. The remaining 14 were in the process of being converted and completion was imminent.

[...]In its November report, Junkers noted that all the aircraft of the three new Gruppe were being converted to 1,900 h.p. and that the work was significantly more difficult at frontline airfields where there were no hangers.

By the end of December 1944 there were 183 Fw 190's in operation with the increased performance modification, and 60 more had been delivered with the MW 50 system and were at the point of entering service. *

New props of 15% more efficiency were also being added somewhere along the line. All of which makes the speeds of the Dora very variable.

The following is from "Yellow 10," by Jerry Crandall:

Page 7 - "The 213 A engine had the original take-off rating of about 1770 horsepower, but could be boosted by various systems to eventually put out over 2000 horsepower. In mid-October 1944, the first production D-9s entered service with III/JG 54 "Green Hearts", flying cover for the first Me 262 jet unit, Kommando Nowotny."

Page 8 - " The main differences between the D-11 and D-9 were the boost in power of the 213 E engine, now rated at over 2000 horsepower, and the change in armament."

Page 11 - "All versions of these three types (D-9, -11, & -13) were to be powered by the Junkers Jumo 213 E engine."

Raises the question, how many D-9's, (if any), got the Jumo E?