EXH MANIFOLD CONV-496-8.1 MZ. Upgrading an exhaust system isn't just about performance-it's about reliability. The Mercury Exhaust Manifold Conversion Kit (866178A02) is designed to replace outdated aluminum manifolds with water rails, transitioning to a more durable cast iron system that improves exhaust flow and extends the life of your engine. Built specifically for MerCruiser 496 MAG and 8.1S engines, this kit provides everything needed for a seamless upgrade, reducing maintenance concerns while ensuring peak efficiency.. Why Upgrade to This Conversion Kit?. Stronger & More Durable - Heavy-duty cast iron construction resists corrosion better than aluminum, making it ideal for harsh marine environments.. Improved Exhaust Flow - Eliminates outdated water rail designs, optimizing exhaust performance for better engine efficiency.. Complete Installation Kit - Includes gaskets, drain plugs, O-rings, and drain elbows, ensuring a straightforward installation process.. Best For:. Boat owner