Is a cooler spark plug required after WI fitted

[weeJohn]

Hello, I have had a quick flick through the forum but I could not find anything that would confirm if I needed to run a cooler spark plug with WI than without.

I am currently using NGK Irridium heat range 8 at the minute, but I am worried the lower combustion chamber temps will reduce their capabilities.

I dont have an EGT fitted as yet, its on that long "to do list" so I am not sure of my current EGTs. Is this the measure I should use to select the correct plug?