this is a more detailed version of the P-120 that I made.

Fire guns with throttle > 95 to use water injection system, this will give you a boost in speed.

The P - 122 was a high altitude fighter/interceptor.
with its large air cooled radial engine mounted behind the pilot, it was both aerodynamic and powerful. while minimizing drag this configuration also made room for its novel turbocharging system.
the innovative engine design gave it both top speed at sea level and superb high altitude climb performance.

It marked the first fighter to be equipped with multiple mk. II flak guns, 40 mm cannons that fired miniature flak shells. While this armament excelled at tearing bombers to shreds. It required a sharp-eyed pilot to hit a maneuvering fighter reliably.

Its Radial engine produced 2100 HP dry thrust, but with its large turbocharger and water injector it could produce upwards of 2500 hp in short bursts. This gave it a top speed of around 450 mph or 740(ish) kmh.

If you want to use the "water injection system" for one of your own planes, just look for the minigun and save it as a subassembly. it should be slightly behind the pilot's seat.