I have a k4j(1400cc) engine that has crankenshaft from 1,6 16v.
I have my ecu remapped and the difference was enormous.
Of course what power gives a reprogramed ecu depends from what other mods your car has.
In my case the programm was made in a Vamag dynamometer and tottaly we have donne about 10 measurments in order to find the best setup.
At the end it gave +7 hp at the peak power,+1,5 kg of torgue.
The difference was in the whole range of rpm.
The limiter went at 7000 rpm.