Having googled this topic indepthly and read many threads on many forums I come to the conclusion there is no conclusion.

So in the none too distance future my 3 Door will be having its final mapping on the new BW 7670 EFR I'm running COP and I usually run it on IK31 but they don't last very long and at £40 quite expensive, currently it has some 071's in to bimble around in and they were only £8.
I always have the gap set to 0.8mm

So what's everyone views then? 071's IK27's IK31's or something else, also I wouldn't have a problem spending £100 on a set of plugs if they lasted

Rich