I created a simple mod to fix the Savage Cub engine which is completely wrong.
The default implementation has a 2.0L (!) while in reality it should have a 1.2L Rotax 912UL with 80hp.
I basically copy pasted the Supralight CTLS engine, which is modeled precisely as a Rotax 912ULS with 100hp.
With some very minor tuning now the Savage Cub flies much more realistically, no more 180kph speeds at 50% throttle or 1500ft/min climb speeds.
As a final note, replacing engine and propeller also fixed the broken CHT and Oil Pressure gauges.