hi mate.
3sgte map sensor is 3 bar (i think)
you will gain nothing, as the map sensor is just for reading pressure and not alter it.
i think some ppl tryed it, and it works.
if u want to boost beyond 1.2ish( the boost that starlet stock map sensor reads )
get it.
for 1 bar boost, the stock map sensor will come out fine mate.
the fuel cut is a ecu parameter, not a map sensor. to raise the fuel cut, u must use some kind of FCD or aftermarket ecu (emanage, power fc etc etc.)