RX7 plugs in RX8??

[Herblenny]

From the other forum

Originally Posted by MazdaManiac

If you are talking about RX-7 plugs (BUR9EQP [NGK-5255], IRE01-31 [NGK-5720]), DO NOT run those in your trailing position. They will bottom out and distort your housings.
If you are talking about OEM RX-8 plugs (RE7CL, RE9BT), do not run trailing plugs in your leading position. They are too short and the electrode design will induce shrapnel.

Either run correct OEM plugs in their proper positions or run RX-7 trailing plugs (BUR9EQP [NGK-5255])in the leading position for turbo applications if so desired.

The trailing plug on the FD is 21mm. The trailing on the RX-8 is 19.
When you tighten an FD trailing plug into the Renesis trailing plug hole, it bottoms out before the gasket hits the mating surface.
This means the base of the electrode is pushing against the housing.
I've seen the damage. Don't do it.