I just bought 8 new spark plugs for my 2000 A6 4.2L V8 ART. The spark plugs are the BKR6EKUB by NGK recommended by the Bentley C5 repair manual. The old plugs are Bosch, and have four prongs. New ones are two pronged and I can't decide if they need to be gapped. My plug spacers indicate the prongs are more than the recommended 1.6mm apart, but the old Boschs aren't gapped 1.6pm apart either. I have never replaced spark plugs and was hoping for some insight.