Now we need to see the results from testing of the 2 types to see if in fact the "S" type is Super as NGK suggests. I recall years ago in a former life dyno tuning a turbo 750 Yamaha engine in a speedway car and being asked to try different types and brands of sparkplugs only to find the basic old NGK cheapies seemed to work best and the expensive Splitfire made less power despite the owner complaining that there must be something wrong with the dyno because the guy at shop told him they made more power.