Are these pre-gapped?

Most NGK Iridium IX plugs come pre-gapped for their listed application. Always check the gap against your engine's spec and adjust carefully, since the fine tip bends easily.

How often should I change them?

NGK rates the Iridium IX for long service, often well beyond standard plug intervals. Follow your owner's manual, and inspect the plugs sooner on a tuned or oil-burning engine.

Will they fit my car?

Fit depends on thread size, reach and heat range, not on the brand alone. Match the part number to your engine's specified plug before buying.

Do they add horsepower?

On a healthy stock engine, expect little or no power gain over a fresh standard plug. The main benefits are easier starting, steadier idle and longer life.

The pack contains four NGK Iridium IX spark plugs. No tools or gapping gauge are included.

Iridium has a finer center electrode and generally lasts longer under high load. Platinum is cheaper and fine for many stock engines; iridium suits tuned or hard-driven cars.