I boiled a stant 195 and it didn't fully open at 212*F in boiling water. My autozone cheap-o 180*F thermostat cracks at 180-181*F, and is full open by 195*F, linearly opening between those values. Actual temps hold between 179-182 in cruise, up to about 185 at the track.

Unfortunately, a 180 degree thermostat has offered me no improvement, save for the ability to change a thermostat without spilling a drop of coolant anymore.

My datalog shows a few points of IAT (sensor on the cold side IC tank) spiking to about 114, coinciding with (as in, followed by) coolant temp increasing. I'm not quite sure why this spiking is happening, because it doesn't happen on every boost event, and it doesn't seem to correlate to any given condition - TPS, speed, RPM are all varied much more often than the spikes. Ambient was about 84 and baseline IAT was 94. At 94, coolant temps stayed about the same, but whenever IAT spiked, the coolant moved up a bit and stayed put.

With the filter on the turbo, I'm wondering how much heat is being removed by the intercooler, then pushed into the radiator, the sum or difference of which is going into the filter to be removed and replaced all over again. I've seen a lot of builds that have the filter mounted like this, but I believe my engine compartment is more airtight than most due to my retention of AC and PS.

did you actually do a compression and leakdown test?
what were the results for each cylinder?

I didn't do a full test; it was just pressurizing the cylinders to see if air got into the coolant. It would be interesting to know the numbers, though.