Mercury - Active Trim Kit (Without Trim Pad) Dual Engine 3.4L V6, 4.6L V8, 150HP FourStroke & OptiMax 150-250HP 8M0129440. Overview. The Mercury Active Trim Kit (8M0129440) automatically adjusts both engines' trim through your VesselView display, giving you full SmartCraft control without a separate trim pad. Designed for dual-engine setups, it works with 3.4L V6, 4.6L V8, 150 HP FourStroke, and OptiMax 150-250 HP outboards.. Active Trim constantly adjusts trim based on engine RPM and boat speed