Vivid Racing carries 1 step colder iridium spark plugs by Denso for your Porsche 996 C2/C4 3.4L 98-01. These plugs are designed for cars running more horsepower. As you increase power, the need for a faster colder spark is necessary for proper tuning. These spark plugs are a great upgrade for all cars in all stages. They are sold INDIVIDUALLY. You need 6 for the 996 Engine.