Dario, the boost gauge isn't very precise but it is a good indicator. If your gauge shows max. 0.6 bar only, there is something wrong. It should show at least 0.7 bar, 0.8 bar is even more common. Don't look at the gauge only during hard acceleration at high rev. Usually, the max. boost figure appears at lower rev in lower gears. It should show more than 0.6 bar at certain situations. Try again and pay attention very carefully!