I wouldn't consider a resistor plug on this system too high. At ~ 25 KV , 5 K Ohm isn't much. I am assuming that these cars use solid core wires correct? If so that gives the stock system 3 K Ohm and perhaps 8 K ohm with resistor plugs. A typical American car has resistor wires and plugs ( Even point type ) with a longer wire reading 12K ohm.

I haven't measured a resistor plug in ages so I can't confirm the 5 K value. ( Sometimes the resistor would fail open )

I'd suspect the market for non resistor plugs is pretty small so some substitution is going to occur.