The company provides two long wires with a factory installed coilpack connector on both ends of each long wire. You determine optimal length of each individual wire, cut it, and then make the four sparkplug end connectors. That was difficult with the extremely tight spacing between the wire and metal receptacle. I tried all the tricks and was slowly destroying the end trying to pull it through. Ultimately, I reamed the 7.2mm aluminum receptacle to 7.5mm and was able to successfully stretch pull the correct length of 8mm wire through so it could be cleanly end-cut and threaded with the spring and rubber washer.
Their plug EARHM38SE
Shave a cone shape to allow pulling through the receptacle then square off the ends.
