A set of Maruha’s standard spark plug cord and plug with a very reasonable price.
The standard plugs for Miata/MX-5 are #5 and 6.
However, when thinking about tuning or knocking many users would like to use #7 and 8.
In that case the #7 and 8 from the IRI-series are the standard.
Lately #7 has been added to the Iridium IX series. Its efficiency is almost the same as that of IRIWAY.
Maruha’s choice is the IX-series.
The iridium electrode is extremely thick (0.6mm). It is possible to reach high performance and very good reliability.
Iridium belongs to the same precious metal group as gold and platina. Its melting point is around 2450 °C, which means that it is strong against heat. Its durability and corrosion resistance are very good what makes its efficiency unchangeable.
NGK’s power cord is a low resistance type cord which means that it is a usual one.