I've had my 2006 Audi a3 3.2 quattro dsg for 5 years now, and every year or so I will have an issue with a misfire on cylinder 6. It is always cylinder 6. I use the recommended NKG IZKR7B(7563) plugs. I often find that the cylinder 6 plug has a crack on the ceramic insulator around the electrode. On one of the plugs, half of the insulator is missing. Replacing the plug always fixes the misfire. I also noticed most recently when I removed the damaged plug, it was very hard to turn and some of the aluminum from the head has fused to the threads, leading me to believe that the cylinder is getting too hot.
Cons: cracked ceramic insulator, insulator missing, fused to head
