It was kind of insinuated, but if you look at cross reference charts you will be able to see it.
This is the thread I made similar comments on:
https://forums.maxperformanceinc.com...=885230&page=2
So an XR5 plug roughly translates to an AC R45S, and an XR4 roughly translates to a AC R43S. The AC R44S falls in the middle.
https://ngksparkplugs.com/wp-content...rence_2019.pdf
When you say '2-steps colder' it has a different meaning in one brand than some others. That's the point I was trying to make.
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