Plugs - Explain it, im stupid!!

[Steve Burnett]

I have just ordered 4 BUR7EQ / NGK 7 plugs from Andy (Cheers mate)

I do have a question though, I do not know much about the plugs the RX7 needs and the term leading and trailing. I know this must be a stupid question but can some one explain this. I know the plugs are correct for the car but should all 4 be used (leading and trailing).
Just to let you know the only mods my car has is an M2 induction kit and Blitz back box.

Thanks
Steve

[fro]

as far as I know, 7s should be used as leading side only. the trailing side should be 9s. It seems that a lot of people are using 9s in leading and trailing (including me now)

[fro]

just found this thread, it\'s very useful

[20B_boy]

7\'s s/b leading (i.e. bottom plug holes) only. Stick 9s in the trailing holes.

[Steve Burnett]

Thank you, you are both gents!