You won't be hitting 1 bar on a stock ECU, without a fcd or piggyback ECU. Are you 100% its stock ECU?
Regardless of what mods are there that will increase boost / boost creep, you will hit fuel cut at around 0.85 bar, the ECU won't let you go any higher. Is it maybe possible for a faulty map sensor / wiring making the voltage signal lower?
First hunch would be faulty boost gauge. Have you any way of adjusting the boost that would make you hit 1 bar anyway?