-1 colder heat range for better knock resistance and misfires
Iridium tip electrodes are tougher than stock Nickel-Copper
This NGK spark plug is an upgrade for N54 engines running higher boost. The colder heat range will lower combustion chamber temperatures and resist knocking and eliminate misfires. The stock plugs produce too much heat with higher boost levels and misfires and knocking (pre-detonation) occur. This NGK N54 plug is one step colder on the heat range scale. It's also a stronger iridium-tipped plug instead of the stock Nickel-Copper for more consistent performance under high boost.
The replacement interval with these plugs is about half the OEM Bosch plug. These plugs will need to be changed every 15-20,000 miles.
Just like ignition coils, spark plugs are key to the performance and efficiency of your BMW engine. A bad plug(s) will harm performance and fuel mileage and affect drivability and engine smoothness. Unburnt fuel in the exhaust will shorten the lifespan of oxygen sensors and catalytic converters.
Video: Replacing Spark Plugs on E9X 335 (Courtesy of SeanS54):