Hi Steve,
When carrying out an output test, the test duty will not take the polarity setting into consideration. If you request 40% duty, the normal output will test at 40% duty, and the inverse output will test at 60%.
I have attached a screen grab of a time graph for the behaviour of the normal and inverting output doing a sim run up to boost with the polarity set to normal and inverting.
As for populating a feed forward table using an air line, it will not be particularly effective, as it ignores engine efficiency, exhaust back pressure , turbo efficiency and many other factors. Correct setup, some sensible starting numbers in the feed forward table and a slightly aggressive integral gain will get the boost to the aim fairly well, and allow you to pause your time graph and quick calibrated your feed forward table numbers.
Perhaps watching the HPA webinar on setting up boost control on M1 is a good place to start:
https://www.hpacademy.com/previous-webi ... -motec-m1/