That sounds great, many have tweaked the AGS setup over here too.
You gained 10 PSI with adjusting the oil viscosity and with a couple of additives, bravo.
2.2 bar to 2.9 bar is about 32 to 42 PSI.
For the cold start after several days scenario, try the flooded engine start technique for no more rattle.
Whenever my truck has sat idle for several days, I hold the accelerator to the floor, step on the brake and press the start button.
After 4 or 5 seconds, I release the accelerator and the engine starts fast and quietly with no irregular noises.
.