I’m not completely sure but from what I see on the wiring diagrams I have access to the BCM (Body Control Module – it controls the operation of some of the electrical units, wipers, turn signals, washers, lights) operates the turn signal lights directly from its output terminals based upon signals received at its input terminals.
These units are normally controlled by internal software and in the case of the flashers will provide an output to drive the lamps at a rate determined by that software (as with the clicking noise you hear when your indicators are on)
Since led’s take far less current than a normal flasher bulb there would no danger of overloading the BCM o/p so no resistor required because of this. The LED however will normally require a resister in series with it to limit the current available from a 12v supply ie the o/p of the BCM (they work on something like 2v therefore the resistor has to drop 10v to protect the led itself)
Older cars using the old style flasher unit (which the Z doesn’t have) would probably require a resistor to control the flashing rate. I would imagine that replacing the flashers with leds would work fine so long as you are sure to connect the led’s correctly if connecting more than one to each flasher position.
Bit of a spiel I know but the best I can do to help. If anyone else is more up to date than I am with the old electronics theory involved they may jump in now to help