I've tried to fit some cr9eb plugs in my 998.According to the ngk catalogue these are the right ones. The plugs are the correct thread and fit the head but i cannot get them to tighten up and get a good seal. I have put them next to the old champion ones that i took out and noticed that the nut part on the ngk ones is shorter which is not allowing the plug spanner (tried various types0 into the head far enough to tighten them up.
Anyone else come across this or i've got the wrong plugs or something's not right with my head. And i don't mean the one on my shoulders.
I have the same problem. The radius at the base of the plug gallery pushes the socket off the plug hex..... You need a very thin plug socket or taper the end of the one you've got.