PERFORMANCE SPARK PLUG MERCRUISER&nbsp;3.0LX Stern Drive 4-cylinder GM 234wGR15ZC234ht 1. Higher HP and torque by up to 3 % 2. increased economy by up to 5% 3. 360 Firing Technology 4. Improved acceleration by up to 15 % 5. 25,000 miles - 40,000 km duration