Originally Posted by
lzylst
They original plug was probably a 7 huh. Due to little higher compression and more aggressive fuel/timing maps than a usdm motor.
The 7 will use more fuel, run cooler, and help if you have any detonation.
never thought of that lol I cant remember if the specs I was looking at was for JDM or USDM. Whoever owned it in Japan put in NGK Iridium R 7 heat range.