Sorry, my post was aimed at Oldtech. Why would iridium plugs cause back firing? An unadapted timing map (too much advance ?) is more likely to cause this than a plug, in my experience…
At me ? What filthy piece of dirt have I done now ?? [ ...... just kidding around with you here , as I'm sure you know ..... )
I fitted Iridiums and red Magnecor HT worms to my standard 996 a few years ago and it never misses a beat.
