Four years ago I had the same problem, I wanted to have iridium but I didn´t find them with projected tip. But in the end I found the NGK IZKR7B (some audi application), looks a little different but the spark-gap is in the same position like the OEM one.
But meanwhile there is the NGK ZKR7AI-8 availible that is used by Fiat for the CNG-Variants of the 1.2l 8v engine.
Interesting - thanks for posting this.
It's a shame you weren't around at the time of the original thread - you have a lot to contribute.
It's hard to measure precisely from photos, but it looks to me like the tip projection on the IZKR7B is longer than on the OEM ZKR7-A-10. That worries me a little, as clearances are tighter on the higher compression Euro5 engine and if a piston crown were to hit an Ir plug it would likely wreck the engine. I know yours has run fine for 10k miles, but clearances vary slightly from engine to engine and also on the compressibility of the plug washer and I'd hate to see anyone else try this and be less fortunate.
The NGK LPG8 does indeed look interesting as it has an identical form factor to the OEM ZKR7A-10 - I don't think these plugs were available at the time of the original thread. The only downsides I can see are that the heat rating is likely wrong for petrol (LPG burns hotter & LPG plugs are therefore designed to conduct away more of the heat), and the cost - they're almost three times the price of the DCPR7EIX.
The original logic behind the decision to go with DCPR7EIX was that the form factor is identical to that used in the Euro4 1.2 FIRE and slightly shorter overall than the OEM plugs (so they were certain to be physically safe). The consensus view was that the slight difference in the cylinder flame placement point was unlikely to make much difference, particularly since the ignition point jumps all over the place on the Cu core plugs (see the pictures of used plugs in the original thread).
I was the 'guinea pig' who first tried the DCPR7EIX in the 1.2 500; several others have now also made the conversion and the collective view is that they work fine without issues and are also good value for money; less than £30 a set and plug life will be at least 40k miles. For everyday road use, IMO they're the best compromise.
If I were going to use a 1.2 on the track (why would anyone do this?) or for very hard motorway driving, those LPG plugs look tempting, even at £65 a set.
