different brands of plugs are not the same eg a 7nova is not a 7rb, i didnt really think it was a bad thing to lean it out some more, with a colder plug you can lean it out quite a bit more than say with a hot plug, (that i only with my limited experience dont quote me 100%). if you are looking for a different brand of plug to run, i have changed to O'donnel in the RB tc10rc and nova 3sct-tuned and i have had good results with these plugs, they last for ever.
mitch