[PeteKz]

Scott, I know you have a lot of experience racing, so by all means, run the plug that works best in your engine, especially for a race engine. I'm just saying that the electrical conductivity of the materials is insignificant in the total picture of what makes a plug good for your application. Thermal conductivity depends more on the design of the plug--how long the electrodes are, how short the insulator is, the shape of the electrodes, how far they protrude into the combustion chamber, the heat range of the plug, etc., than the inherent characteristics of copper or nickel or silver or whatever. I'll bet that the Brisk Silver plugs have very little silver in the electrodes. Silver would erode away very quickly due to heat, so it must be some alloy with lower thermal conductivity than pure silver.

Whatever works best for you, go for it. Just don't go shopping for plugs based on marketing claims about the materials they are made of. How those materials are combined into the overall design is far more important. And that applies to race plugs or street plugs.