where to tap in for boost gauge - MC I5?

[Fuzzzydog]

I seem to be having some overboost issues with my 88 5ktq avant lately.  The
car is a rocket, ever since I swapped out a suspected faulty wot/idle switch
for a known good one.  I didn't realize it was quite sluggish previously.
however, now a problem has manifested itself and that is that I seem to be
hitting the overboost cutout, without really even getting into the gas.
sometimes when I am mildly on the gas holding a steady speed or slowly
accelerating it will surge ahead quite forcefully. I actually think there is
something wrong with the engine management that is giving me too much power
- it is just that powerful.  (I've been driving late 80's I5 turbos for
about 8 or 9 years now)

so I have an aftermarket boost gauge to help with diagnosis, which I believe
will support the overboost feeling.  if confirmed I will dig into the
wastegate and see what is going on in there.  but the question is - where
have others tapped into the intake system for an aftermarket boost gauge?