Kevin, Long ago I bought a PJ Grady major tune-up kit and was given the option of getting either copper or silver tipped Bosch plugs. The silver were of course more money and better quality, so I opted for those. They are model HR6DS. Oh if only I had the time to install them! If you opt for the PJ Grady stuff, order it through DMC Joe. He deserves credit for all his effort on the list here. You got me curious about using the micro-washers/shims. I've heard about using these before but never tried it myself because I didn't know which way the gap is supposed to point. If you find out, let me know. Does anyone know a good place to buy these? I've seen them in a Jacob's Electronics catalogue, but I would rather buy them from a D vendor or get them locally. The HP gain is very small, but in the Delorean's case every additional horsepower counts. Walt Tampa, FL