My question is, "what was the reading prior to you fitting the gauge?"
Now, the answer is obvious, hence fitting of the gauge.
The point being, that if there wasn't a problem prior to the gauge, and the car is running normally, is there a problem at all?
IIRC, the ECU will shut the engine down if it detects over-boost, and with the previous comments from out learned colleagues, I would say that you might have a slightly inaccurate gauge, or are just lucky that you get a bit more bang for your buck.
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