The obd1 injectors should read ~12ohms and not require a resistor box. They are considered high impedance.

The obd0 injectors that require a resistor box usually read ~2-3 ohms.

An obd1 ecu WILL run on low impedance injectors without a resistor box. But over time the injector drivers on the ECU WILL burn up. I have heard (but never personally verified) that they will run slightly richer without a resistor box too.