I overboosted an engine in a Mooney 231 - do I need to do an inspection?
This most likely warrants a call to Don Maxwell the veritable Mooney expert but I would for sure have the engine checked by a Mooney expert or someone that knows their way around the TSIO-360-GB. At the minimum a compression test and possible borescope check is in order. 

If you have the early 231 in its original config you have a fixed waste gate that can be over boosted on takeoff.   


  The engine also had a fixed wastegate in the exhaust system, meaning
  careful pilot technique was required to keep from over boosting the
  engine on takeoff.  If the pilot inadvertently added full throttle for
  takeoff or a go-around, the engine would over boost, with only a
  mechanical pop-off valve in the induction system to save the engine
  from literally coming apart on the runway.  Fixed wastegates also mean
  high turbocharger speeds (RPM) at altitude, which reduces turbocharger
  life


I don't know much about the gauge itself but it may warrant checking it to make sure it is operating properly. 

You can also reach out to continental and ask them what the over boost limit is. There is a chance they have some data on it or can let you know of a good course of action.