plugs???????????

I don't know any hard and fast rule and as stated above it just what works for you after some trial and error. My self I use Bosch W7D for racing and Bosch W9D for the street. Why? Because these are the old copper core plugs that fire better and cleaner than the newer resister type plugs and because I have been using Bosch plugs for the last 30 years as an import mechanic.

P.S. don't use platinum plugs for racing as they will misfire at high rpm and load up ...just my experience with them