There is no such thing as a 'safe boost increase'.

If you have a bugeye, you will need a retune to increase the boost, which will make sure the correct fuelling, timing etc is in place to match the increased boost level.

Search for ECUTek or Verso.

I've 'safely' run 2 bar of boost on a GD wrx as it was tuned accordingly.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]