I've been out of town and finally catching up on the mail.  I've flown about 190 hrs on the original plugs that were in the RX-8 Renesis engine when I bought it from the auto salvage yard.  The engine had 9300 miles on it and the plugs were original Mazda Renesis RX-8  RE7C - L and RE9B-T .  I've used 100 LL for about 10 of the 190  hours but normally use Mogas.   So far the plugs are working great.  I think I remember Tracy used the same type plugs in his Renesis for over 400 hrs.

Dennis H.
RV-7A-- Renesis