Larry, I agree with Page; why bother. The Platinum plugs likely have some iridium in it as it's used to harded the platinum during processing. I love the AC Rapid Fire plugs too. Save the $$ for something else. (Next thing you know it'll be Dilithium Crystals!!) Beam me up Captain.
Denso plugs are great for table talk but IMO they're a waste of money. They do nothing and in severe cases of detonation they are in fact so tough it could ruin your engine. W/ ordinary plugs the temps would burn the plug so it would seize to function, with the iridium or platinum plugs it will simply keep on firing. Then again, if you have to rely on spark plugs giving up to save an engine from detonation... you get the idea
I run Champions, they work fine for me. Regular AC R45TS work great too.
Hey Derek, a go kart eh?
Here it still has the old Honda EVOII 360 4 stroke
And here the Hirth 725cc 2 stroke w/ 2 Bing carbs & dual exhaust cranking out around 125Hp