I may be wrong but all this "specific" spark plug nonsense is exactly that.
Im guessing a lot of folk have bought these, when actually a set of OEM plugs would have been absolutely fine.
There is a back to back dyno test on VAGOC looking a Okada coils
Compares OEM coils/OEM plugs vs. OEM coils/uprated plugs (can't remember which but think they might be these very ones) vs. Okada coils/OEM plugs vs. Okada coils/uprated plugs
Verdict - plugs make a difference. I think the Okada/uprated plugs was making 15bhp more or so. Most of this was down to the coils, but there was a measurable difference between the plugs in all set ups
anyway, even if they made NO difference they're cheaper than OEM so there's still no reason to go OEM.