I was just wondering that if mazda is now recomending trailing plugs in both leading and trailing holes on the new rx8s does that mean that we can use re9b ngks in our n/a's? just wondering.

 

The only differance is the heat range, typically the leading are colder. In high boost or performance motors people run hoter plugs in the T typically the same as the L. Earlier modle rotarys like the 12A ran the same plugs in L and T.

 

Actually the last revision I got for the RX-8 plug was to use the NGK RE7CL in the leadings and the NGK RE9BT in the trailings.

The only time they were recommending the RE9BT in the leading postion was back when they were having issues with the RE7AL and RE7BL.

I use re-gapped (From .048 to .035) RE7CL in my leadings on all my FC's now. They are half the price of the Denso IRE01-27 that I was using in my leadings.

The only reason you would want to use a colder plug like the 9 is if you were having detonation issues and/or your average starting temp never dropped under 80F. Otherwise with a stock or near stock system, the car would be much more prone to flooding and cold start fouling with the colder plugs.