The K-1 was equipped with GM 1 nitrous oxide boost, which increased the K-1s maximum speed by 84 kph at 8,000 m at a rate of 100 g/sec. With 50 g/sec the aircraft's operational ceiling could be extended from 8,400 to 9,800 metres. But failure rates of the GM 1 were very high and attention was shifting to other Do 217 variants. So the use of GM 1 soon stopped. Serious shortages of the BMW 801 led to the cancellation of the K series. However, tests with BMW 801ML Motoranlage unitized-mount format radial engines added a supplementary command unit to the usual 801 Kommandoger�t engine control unit for each radial, which could engage the booster switch, ignition timing and the weak-rich mixture control automatically, which made the 801L powerplants easy to operate. Oil pressures also triggered the VDM propeller. The blades themselves were 3.9 m. A 3.8 wooden propeller could be used as an alternative although with a slight loss of speed.

The standard 2,165-litre fuel tank could be supported by two fuselage tanks with 700-litre capacity or external tanks with 300 to 900 litres. An all-up-weight of 15 to 16.5 tonnes could be expected. The K-1 would need some 850 to 1,110 m to get airborne. Taking off from a grass strip, an altitude of 20 m was reached after 1,500 m and from a concrete runway it was 1,300. With two auxiliary tanks its speed dropped by 4.5 percent, and with bombs, by 6 percent. Flame-damper equipment also caused serious speed reductions; 7 percent in level flight and 9 percent when at operational ceiling.