Forget tuning individual injections (3 to 10 per cycle); it's a piezo and the whole system is lubrificated/cooled by the fuel. Don't touch this, I dare not on a ship sized one (many orders more tolerant and resistant) so a car sized one is like modding a Swiss watch with a claw hammer.
If the engine is stock, modding it like you imply can only yield results within the tolerance - if you are lucky - 5% max. Anything more is fantasy, as a colleague of mine discovered when he destroyed litteraly every part of his engine upstream of the clutch on his Ford Galaxy; the specialised garage in Luxemburg told him to leave at the lowest level, he turned the nob to 11 and nuked it in 4 months.
But that does not mean that your idea could not have uses in "overall" management: if you change the airbox, filter, booster pump, intercooler etc... The ECU might not "understand" the implications so modding the values of airflow, heat etc it gets to make work in it's standard tune but at a higher power level might be needed / work.
But beware, more and more sensors are digital... So just amplification both positive & negative is going to do bugger all in your engine's Unicorn Output.
And a last thing, that most people forget: a 10% change in Hp implies modifying the cooling, if you don't, your engine will heat soak and reduce it's lifespan. This does not matter if you reside in Iceland.