Hi John. We just seem to get lots of cars in with ignition problems, We have had dozens in with various problems, from electrical interference upsetting iac valves, misfires, and we have even had 2 towed in that would not start even with new NGK's fitted. We have now started having bets as to what plugs will be fitted, and they are usually NGK, we take them out and chuck them in the bin and fit Bosch, and luckily we haven't had any problems with them. I have heard various stories, one explanation was that there may be some fake NGK's about, but that has not been confirmed. It may just be that there are millions of ngk's about and we have come across a few bad ones, but we can only go on what we have seen. I know that there are lots of garages out there that swear by NGK. Has anyone else had any experience of anything similar. ??