John, There is a multitude of sound reducing
materials on the market. The shapes of the air intake assemblies is also limitless. Their in lies the problem. Most sound baffling materials impede the flow of air. Air currents do most their flow next to the passageway walls. Thus a foam rubber with peaks and circular valleys (like egg crate pads)while doing a good job of reducing noise also reduces air flow. Like, stops air flow. Entries with curves, bends, sweeps is a little better but also bad. Have you tried a good intake air filter such as a "K&N" filter? While boats don't need air filters like cars, they will not hurt a boat engine. I would venture that a good K&N will reduce noise by 40 to 55 percent at mininum. Also talk to someone at a good high performance muffler shop. They know how to reduce noise with baffling only without impeding air flow. Let me know how you work this out. Ray S/V Speedy
