For all member who plan wanna to change spark plug, pls becareful on heat range, which is recommanded from factory, from std heat range change to higer number range plug ( cool plug ) u will face carbon remain , if change to lower heat range , pre-firing/ knocking will occurred in ur engine.
Doesn't mean the higher number u use, is good for ur car.
For example mivec engine;
it run with 11.0 compressor ratio , oem spark plug heat range is at 7, how about for those normal SOHC 1.3 /1.5 and 1.6 engine ?? IS too much over limit to use on this heat range plug.
Material use is just to extend on plug tip melting point, doesn't mean it will give u extra more power ....
For myself, I use only 8.2mm cable with std NGK stock from mivec halfcut spark plug only ... just replace the spark plug every 10kkm.
just my opinion.