Some more Spark plug info from Import Tuners Magazine

[ned032002]

Check this out---If it's too hard to read you may need to save it to your computer and then open it up so you can zoom in a little closer to it

[david-b]

Ya for Iridiums!! I win

[Thor06]

2.9 hp! DaTz MaDd TyTe Yo!!1!

[ned032002]

That's not bad for such a simple upgrade

[Thor06]

A 400 hp motor isnt going to put down 400 hp every single time Ned. I'd put money on those plugs doing next to nothing for actual power and the extra power coming from one or many of the countless other variables in the power equation.

[JoeShmoe]

Its too hard to read, I'm not even going to try to make out what it says. But I went with Ir just for the longevity of it, not really for the power. I've heard that they maeka hotter spark with more hp but I higly doubt they make more power for a long time.

[LandoAWD]

Waste of paper. Save your money and put factory (or one to two ranges colder if needed) plugs gapped to spec.

[Killa]

after own many type of car, I learn that put the plug that made for that car, like

japan use ngk
ford use auto lite or motorcraft
gm use ac delco
chrysler use champion

I still use ngk for my procharger stang .