The process is quite simple.
1) Disassemble the enclosure of 12V Boost circuit
2) Find 2 resistors that are in series from 12V to GND, there common point is Vref
3) Replace the one going from 12V to Vref with slightly higher one(in my case original was 300kOhm and I replaced it with 325kOhm(420k+480k on top of each other))
4) Verify that the output voltage is around 13.2V(likely anything from 12.8-13.3V should be OK)
5) I cut the round part of banana plug cover to keep just the cable strain relief
6) Put it together and you have a Mavic Air travel charge