What the manual is stating there is overboosting and detonation are possible below normal permissible MAP, so pay attention and reduce throttle if that’s happening.
It looks like you reworded what your mod does? I remember it saying something different. I’ve been known to be wrong, however, lol. Be that as it may, Is there a pin in the MP gauge in real life? That seems dangerous to me and I can’t imagine they’d do that.
Point is, pilots don’t need help. They are supposed to know their engine and operate it within the limits recommended by the manufacturer. It is well known that you’re not supposed to push radials beyond their limits, and the controls allow you to push them beyond their limits at sea level, because the same positions at altitude don’t push them beyond their limits. Not to mention there are situations where you want to overboost, albeit for very short periods. But when your life depends on it, blow the engine.
I’m not meaning to be critical here. It just surprises me that this would be the case that there would be a pin in it.