The HD power steering pump delivers 1,800 psi of pressure and a flow rate of 7.5 liters per minute, capacity designed to address the demands of high-speed, dual-engine catamarans executing extreme maneuvers. The new 80cc High Flow helm reduces lock-to-lock steering input on dual-engine catamarans for more-responsive handling, and reduces the ratio on boats powered by triple, quad, and more outboards that use more steering cylinders. The HD pump may also be used with Mercury 40cc and 50cc helms, but the 80cc helm requires the HD pump to meet its flow requirement. The increased pressure and flow of the HD pump can also improve the power assist function on boats running multiple non-surfacing engines, including multi-engine pontoons.
Content extracted from https://www.boatingmag.com/story/boats/mercury-racing-hd-steering-pump/