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.Densos Iridium power spark plugs help your vehicle achieve unparalleled performance. It alters the belief that a mere spark plug can add power and mileage. This is done by combining an Iridium center electrode with a tapered cut U-groove ground electrode. Iridium conducts electricity better than platinum, however what makes it exceptional is its also 6x harder and 8x stronger than platinum. This ultra-fine iridium center electrode provides superior ignition performance during acceleration and top cruising RPM. The U-groove ground electrode creates a larger, brighter flame kernel. The tip of the ground electrode has been tapered which further improves firing performance by reducing. All of these features combine to give more horsepower to your motor.