pulsewidth viewed through the OBD2 port isn't actual PW at the injector...
tuning can actually be sending more or less than the displayed(scantool) PW to the injectors, since there are plenty of tuning tables which use multipliers/adders, etc to the true/commanded signal to the injs.
an oscilloscope is the only accurate measure of electrical pulsewidth...though injector build practices can & will affect the true, mechanical on time of the injector.
There is always mechanical delay...from the time that the signal is received by the solenoid, until the nozzle is opened (by the injection pressure). Changing the specifications around the armature can reduce or further lengthen the delay of the nozzles' opening.