Peak boost will vary based on OAR (Octane Adjustment Ratio). If the car is knock free on your gasoline it will run up to about 19psi peak (not constant). But it you have a low OAR rating it will usually target lower torque output and use the reduced tables for about 14-15psi.I tend to see 18-19psi on mine in stock configuration. This is on low octane fuel and @ 5,200ft elevation, reading from an auto agent 2. Not trying to disagree, but curious if there is maybe a different PSI sensor that the auto agent is pulling from? I've pulled up MAP and it tends to follow based on atmospheric pressure to match up to 20psi spikes.
You won’t be seeing that 19.9psi at redline on the stock tune. But you can see that and more with a tune (whether from JB4 or ECU flash)