i understand the main reason for changing plugs is to compensate for higher boost and other mods.if the change is to a colder plug why not just get a 1 or 2 size colder stock plug.why are these more expensive plugs supposed to be so much better and are they worth the differance.ive used autolites all my life and had no problems.

 

Our stock plugs are platinum which is known to hold heat, this can lead to pre-ignition and detonation. Copper core plugs or Iridium are much better for performance engines. You don't have to spend a lot of money if you don't want to NGK make one of the best and they are not expensive at all. As far as brand look at this misfire chart that was post by someone a while back.

http://www.supercrewdriver.com/galle...0138&anum=1351

For more info check out this
http://www.centuryperformance.com/spark.htm

 

I'm running Denso's.AS you can see from the misfire chart they are the best.
A little expensive,But IMO worth the extra fifty or so Dollars for the "piece of mind"
I have melted down stock Platinum plugs in my previous "L".
Now I have an EGT gauge and have Dyno'ed to insure a safe a/f ratio.Although at 11.9 to 1 at full boost i'm running about 1300*F.
I believe Steel melts @ about 1400*f.