Piston engine model vs temperature

Greets,

After comparing the piston engine model to real world data, ive noticed that the model is around 0.3% weaker per degree celsius colder. This adds up as you climb and as it gets colder.

At sea level the power settings work perfectly.
However eg. at 14k feet (-11°C) setting 45% based on MaP and RPM im only getting 40%.

Can we have a temperature to Mechanical efficiency table?