A single bar map sensor cant read boost. The Ecu wont know there’s boost. A fuel multiplier just increases fuel pressure in a non-linear curve to match the extra air.
If the multiplier doesn’t do enough, you just need to momentarily “alter” the cts value to enrich to mixture with pulsewidth from the coolant temp table.
These tricks don’t work with high rpm/ high boost.
This is ancient tech, but would work with this application.
I had a problem where I ran around with lots of fox body mustang guys years ago. The things people do to trick the computer was funny. One of the weirdest ones I saw was a dry nitrous kit that applied nitrous pressure to the fuel regulator to close it off and boost the fuel pressure when the nitrous was on. Things like that and the "Boost a pump" that cranked more voltage to the fuel pump. All in the name of not letting the computer know what was going on.
That is why I used to be scared of EFI lol.
