Hooked up the pressure sensor to the exhaust manifold once again to measure the pre-turbine pressure.  I have not confirmed that the pressure sensor is properly calibrated, but the results shown below are probably in the ballpark.

The EGT is flat line because that is a probe located external to the exhaust manifold with the purpose of measuring the temperature near the surface of the exhaust manifold.  With a small air gap between the sensor and manifold surface, and 40 deg outside air to cool things, the region near the exhaust manifold was not very hot during this pull.

Here is the setup I am using to log the exhaust gas pressure.