cheers, are we suggesting then that the iridium is the one to have on a remapped car?
in regards to the NGK BKRs, they are an uprated spark plug over the others listed as OEM equivalents. the fact that they're iridium isn't so much the point. it's more the fact that they run a little colder, and by doing so stop predetonation and thereby give smoother running.
8 is colder than 7, and on this basis people recommed the 8 for tuned cars, and the 7s for standard map cars. the reason for this is that apparently non-tuned cars won't get warm enough to burn deposits off the colder 8s, and lead to build up on the sparks plugs and rough running.
they will fit the TFSI - i'm running some, and in the link above are details of the correct BKR8IEXs to get and reviews from dozens of other people with them.
the Nology ones are silver, and they claim that they work better by being a better conductor of the spark and hence give smoother running.
both the Nology and the NGKs work out cheaper than OEM. so whether they're better or not, they're still worth having
. at the £25 - £40 they cost they can be considered a throw-away item and can be replaced annually with no real effect on your wallet (compared with some other service items at least
)