I slapped a set on @ $6 per plug. My conclusion after 20K is the iridium is the same as the platinum, platinum 2, platinum +4 and the ON SALE 99 cent autolights. I don't think I'll get over 40K on the iridiumÆs. $1.29 NGK's will give you everything the $6 iridium's will. Unless you need a special plug to run at a certain temperature for a special application don't bother paying more than $1.50 a plug.