T_T are you politely suggesting I remove the Densos and go back to a set of OEMs?
That is your call. However, VW (actually, it is Audi who carry out the vast majority of engine development for the VW Group) test and fit spark plugs from all makes - Bosch, NGK, Beru, AC, even Champion - and then specify the best one. If Densos were as good as they claim - how come NO Densos are recommended by VW or Audi for OEM fitment.
I've been in this game far too long to fanny about trying to chase the 'best' spark plug. I have never, ever found an OEM spec plug to be unsuitable. But I have come across many a non-genuine or non-OEM spec plug which has caused issues.
And Densos seem to have a similar but limited 'enthusiasm' in the biker community - but again cause frequent probs. NGK are by far the best plugs in bikes - from both japs and italians. I won't include Hardly Davidstows - because they are just two-wheeled tractors!
If you have gone for Densos, then I might politely suggest you have been swayed by marketing over engineering.
ETTO, though.