You can set the boost higher than "factory spec" on a standard chip.

The normal boost is 0.45 to 0.55 bar.

This is because when the overboost control is working (the first few seconds of higher boost when you slam it to WOT before it settles to 0.5ish bar)
If you raise the boost it will be too high on overboost and the engine cuts out.

I don't run overboost control anymore because I disconnected the AMAL valve (which controls overboost and boost cut-off if the ACT is too high)