It looks to me like NGK has changed their numbering, can anyone confirm that the post on boostaddict is correct? [I reordered iridium platinums on Amazon and this new numbered plug came instead]

From boost addict :
"The actual part numbers are almost identical. 5992s are ILZKBR7A-8G while the new part number is ILZKBR7B-8DG. The heat range is the same (7) and I would gap them the same. I suspect only a small revision change has occurred.

http://www.ngksparkplugs.com/tech_su...qs/faqcode.asp

ILZKBR7 plugs are premium iridium with a long reach and extended projection. The plug has a double hex head with a 12mm straight thread, a gasket and a 19mm reach. It has a resistor and is heat range 7.

The A changing to a B seems to signify NGK has made a design change to the construction of the firing end.

8 indicates a gap of 0.8 mm (0.032"). But we change this anyway. By their numbering scheme this becomes 5.5.

The G means copper core ground and the extra D means they have changed the specification on the shell plating."

 

Can't confirm the technical specs but just looking at the amazon reviews they seem to work fine for MCS's.