I've been using the Bosch Super plugs in my Jeep Grand Cherokee Laredo(6 cylnder) for a few years. They are copper. They have been fine but I just noticed that Bosch now makes a Super Plus. Anyone try these yet? I don't think these are copper.
http://rb-aa.bosch.com/advastaboschaa/Pr...p;publication=1
http://rb-aa.bosch.com/advastaboschaa/Pr...p;publication=1