Does anyone have any knowledge about these plugs for 930's?

Silverstone spark plugs are especially designed for the unique demands of modern high-performance engines.
For racing or dependability and efficiency for everyday use, Silverstone spark plugs deliver the most powerful spark.
Top Quality Materials. Long Lasting. Cleaner Combustion

The following are from the BERU Silverstone application chart;
Porsche 911 Carrera, '84 > '89 3.2, Motronic B6
Porsche 911 S, SC, '73 > '83 2.7 or 3.0, CIS B6
Porsche 930 Turbo, '91 > '92 3.3, B6
Porsche 930 Turbo, '75 > '89 3.0 or 3.3, B6
Features:

The large diameter silver center electrode of Silverstone spark plugs increases spark carrying ability = Up To 137% More Spark Power
Silver is the best electrical and thermal conductor of all metals, which makes it the ultimate material for a spark plug's center electrode.
Silver is extremely resistant to erosion, guaranteeing a virtually unchanged electrode gap for the life of the spark plug. This greatly extends change intervals. Silver offers the best thermal conductivity giving Silverstone a much wider heat range.
Silverstone spark plugs are designed without a suppressor resistor, perfect for performance enthusiasts who demand the most from their engines.
A multi-rib current leakage barrier prevents arching over on the outside of the quality, black aluminium oxide insulator.

 

If silver is the best then why did the factory choose Platinum, that's an even more precious metal.