Some news.
Seems I was afraid for my car because if just turn the screw for just an amount to only feel more torque and let it as it is.
I explain, I've turn 3 times (in 1/4 turn step each) the screw now in all gears i've constant 0.6 bars, no drop and a few spike at 1.0 bars.
I'm very happy! What a car!
When i turn 1/4 turn more, I have the same boost except that the spike goes up to 1b (like 1.1, i mean the needle goes pass the 1b mark on gauge), seems the limit of this MBC (it was sold to maintain 1 bar... but for 15$...).
Thanks for all support seems the next tape will be an electronic devices but really expensive even old ones...
P.S: I love more my S12, what about you?