As the subject states, I'm curious what the difference is between the PFR7G-11 and PFR7G-11S. As I understand it, per NGK's website, the PFR7G-11 is OEM equipment for the '01 B18C5 and the PFR7G-11S is OEM equipment for the '00+ F20C1(S2K motor). The reason I ask is because I checked the plugs in my JDM 98 Spec B18C-R motor this morning and noticed they were part number PFR7G-11S, which apparently is not the same plug as what the US spec R motors are running. So, what's the difference?

Something interesting that I also noticed per NGK's website compared to the 98-01 Integra Service Manual, is that the 97-98 and 00 B18C5's are listed as running the PFR6G-11, which is clearly a single heat range hotter than the 7F-11's in the '01 B18C5. So, why the change to a colder plug the last year of the 3rd gen ITR's?