Mercury - Active Trim Kit (Without Trim Pad) Single Engine 3.4L V6, 4.6L V8, 150HP FourStroke & OptiMax 150-250HP 8M0129439. Overview. The Mercury Active Trim Kit (8M0129439) gives you full automatic trim control through your VesselView display instead of a separate trim pad. Designed for single-engine installations, it works with 3.4L V6, 4.6L V8, 150 HP FourStroke, and OptiMax 150-250 HP outboards.. Active Trim adjusts engine trim automatically based on RPM and speed for better acceleration, f