BRISK Racing Plugs LR15ZC 6 pieces. I looked for a part number that fits the original 240Z. These are flat-seat plugs, and unlike VX or iridium plugs, they are said to produce a lot of sparks. I used them on my motorcycle and they were very good, so I wanted to try them on my car, but I never got around to it. They're a bit expensive, but I think they're more effective than regular plugs (in my personal opinion). They are new and unused, but thank you for your understanding.