Go to Kirbans website catalog and look up those E-3 plugs. Dont have to be gapped or set and i love them. My car idles and runs better than ever.(also bought new set of his wires.) My GN has very good street manners, and made 509hp at the wheel. good all around plug. They cost a little more, but should last longer. My $.02.
A general guideline posted by Ken Mosher in the spring cleaning guide:
Cars running 12.99-13.50 seconds or faster should use R43TS or CR43TS plugs (one heat range colder) and 12.00 and faster cars should use AC R42TS or CR42TS. The CR designated plugs have a heavier electrode (the "C" stands for "Commercial"), but are otherwise the same as the R42TS plugs. Autolite 24 plugs are also a good choice.
Between boost and nitrous I do get KR with 24's that I do not get with 23's. The new engine has a bit more compression and its gonna have even more shoved down it's throat. That's why I'm asking