I'm "the guy" who made those screenshots posted above. Unfortunately I don't have (or I can't see it) an option for 150kHz bandwidth, here is a screenshot from HDSDR:
So - samplerate stays 192 kHz, but you need to narrow FM bandwidth to 150 kHz (the closest I can come with HDSDR is 150.977), otherwise the mpx output is about 20% too low.
compensate for the 20% offset (in mpx tool for example). By compensating the signal in MPX tool itself you can actually listen and measure slightly overmodulated signal accurately.
Here the measurements I get from one radiostation that has solid signal in my area:
150 kHz BW - pilot 9.5% (+/- 0.1%)
192 kHz BW - pilot 7.5%
And I'm pretty sure 9.5% is accurate
Bojcha used different method, with modified tuner that has mpx output - it's the most accurate way of measuring signals, provided you know how (and are able to) calibrate the whole system, including line input in your soundcard.