Well, that is what I get for using IE... Had a nice long reply typed up and it crashed, loosing it all.

Anyway, my first hand experience with using NGK Laser Iridium plugs in both the SCFI 4.3L v6 in my old 2000 Bravada and the Vortec 4.2L I6 in my 2004 Rainier, I can say that both vehicles had a noticably smoother idle and seemed to run more smoothly everywhere else with Iridium plugs vs double platinum. Idle quality I observed first hand improvements as well as recorded data. This can be attributed to the fine wire center electrode which promotes a much more consistent spark.

Now if all you want to look at is electrical conductivity numbers, then ofcourse, platinum conducts electricity better than iridium, but when you get down to the spark dynamics, a fine wire electrode will produce a more consistent and less scattered spark than a wider electrode. That is the primary benefit of an iridium electrode that platinum just cannot match.

I will add that the AC Delco double platinum plugs were only 5k old in the Bravada (got the NGK Laser Iridiums for free from a vendor here) and the NGKdouble platinums in the Rainier were original with 32k miles on them and I replaced them for S&Gs

 

i think they run very smooth as well

 

You could puta yellow sticker on a civic and he would say its a huge difference I don't care what anyone says but there is no way his a$$-dyno felt a huge difference from a spark plug change