All stock FC3S turbo fuel injectors are rated at 550cc/min.  Kouki FC3S all ran high-impedence fuel injectors; these fuel injectors have an red tops with oval plugs.  These Kouki high-impedence fuel injectors plastic tops normally turn pink due to heat and age.

The Zenki FC3S had mixed low-impedence and high-impedence fuel injectors depending on build dates or VIN's.  The split was made with FC3S with build dates before or after June 1987 (6/87), and last four digits in VIN at ...7601.  Zenki FC3S up to this build date and VIN split all used low-impedence, purple-top fuel injectors; the low-impedence fuel injectors turn brown/tan with heat and age.  Zenki FC3S after this build date and after this VIN split used high-impedence, red-top fuel injectors; these high-impedence fuel injectors turn pink with heat and age.  The Zenki FC3S used rectangle plugs that were not compatible with the Kouki FC3S engine harness.  "Low-impedence" fuel injectors typically measure about 2Ω.  "High-impedence" fuel injectors typically measure about 14Ω.

You can use low-impedence fuel injectors in a car originally designed to use high-impedence fuel injectors by running some 20-watt, 10Ω resistors.  You can use high-impedence fuel injectors in a car originally designed to use low-impedence fuel injectors by jumping the fuel injectors resistor block located at the front, passenger side of the engine bay.

You can use fuel injectors from a 1984-1985 RX-7 GSL-SE.  These are rated at 680cc/min.  Note, the GSL-SE only uses two of these fuel injectors, so if you want 4, you need to find another set.  These are low-impedence fuel injectors.  There are also 720cc/min fuel injectors that are sold by GReddy for $130 each.  These are also low-impedence fuel injectors.  All the above mentioned fuel injectors are drop-in replacements.  You can run other types of fuel injectors, but they will need some modification to fit properly.

Keep in mind, the stock fuel injectors (4 × 550) can sustain about 250bhp at the flywheel under stock fuel pressure (35psi).  4 × 720 will support a little over 300bhp at the flywheel at stock fuel pressure.

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