Yes, exactly what i was looking for !!!

 

Copper plugs are great for spark energy, and are cheap for those who are frequently reading and/or changing their plugs, but they are the worst-available plug material for durability.

What's the Porsche recommended change interval? When I see posts from people claiming 3k plug changes, are they all running copper plugs? That seems way too frequent for an iridium or platinum plug change interval.