Specialty Plugs
This is the age of designer spark plugs. SplitFire rode the first wave of specialty plugs with its V'd ground strap, and now it seems that every spark-plug manufacturer has its own version of what's hot. While the debate will continue to rage over whether diamond-shaped or split-V ground straps are worth more power/mileage/emissions, we do know that plugs using more exotic metals enhance durability. Platinum arrived a few years ago, with Bosch leading the charge with three different versions of its platinum-tipped spark plugs. Then NGK upped the ante with its Iridium IX series of plugs. The plan with virtually all these designs revolves around reducing tip or ground-strap erosion that increases the gap between the center electrode and the ground strap. Some plugs, like the Bosch Platinum +4, use four ground straps to also minimize the overall gap to ground.
The price on these plugs is also significantly higher than for normal copper-core spark plugs, and generally, the heat ranges tend to be limited. These specialty plugs are not intended as race plugs. Instead, they are aimed more at everyday drivers and may offer slight mileage or emissions improvements.
On the left is a standard copper-core Bosch spark plug. In the middle is the Bosch Platinum, while on the right is the Bosch Platinum +4 plug, with four separate ground straps to increase durability. All three are offered in the same heat range, giving you a wide array of choices just within the Bosch lineup. | 
A common problem is interference between header tubes and spark-plug boots. Often, shorter plugs, such as ACCEL's shorty spark plugs, will minimize the difficulties. Other manufacturers also offer shorter plugs, but they are not necessarily called out as such. | 
ZEX (left) has specialty nitrous plugs that offer two different length ground straps. The longer, primary ground strap employs a copper core, while the three shorter-side-gap electrodes keep the tip clean. On the right is the E3, the latest entry into the specialty plug market. E3 claims its diamond-shaped opening around the copper center electrode offers improvements in emissions and mileage. |