I can honestly say that over the last 15 years working on my own servicing cars on a regular basis I have never had a faulty NGK spark plug, even to date if I fit coil packs on Citroens did 4 last week always get them from dealer and they won’t guarantee coil if there plugs are not fitted (SO THEY TELL ME) and they come in a Citroen box but are NGK. I use them on Vauxhalls, Fords, Peugeots etc etc, its very rare I do customers cars that I don’t know most keep there cars 4 or 5 years so I know them and if they went faulty I would be the first to know.Where do all you guys buy your plugs from I buy mine direct from wholesalers never used andrew pages or factors etc etc are cheap copies about seems to me in this world everything gets copied.