I just bought a 92 Supra Mariah and have found that it seems a little too loud for a comp ski boat and was informed by a friend that the exhaust system, for this model year, was run through the stringer system of the boat. I was also told the factory has replacement mufflers designed to fit into the piping that runs from the risers to the floor connection. Has anyone out there used these mufflers, and if so, how well do they work? Thanks.