>It reduced, but did not fully eliminate soot build-up. There's a new device on the market that's being advertised in the local boating magazines called a "Turbulator." It's being marketed by North Harbor Yacht in Anacortes, WA. http://www.northharbordiesel.com/home.htm They don't seem to mention it on their website, but it's a device with curved fins that fits into the rear of an exhaust outlet and mixes the exhaust and water together. They say that as the move down the exhaust line from the engine room, the exhaust ends up in the top of the pipe and the water in the bottom. By mixing the two back together at the outlet the water "traps" most of the soot and takes it into the water instead of letting it escape into the air and get all over your transom. I have no idea if this thing works as advertised or not, but you could contact North Harbor and find out more about it. ______________________________ C. Marin Faure GB36-403 (grp) "La Perouse" Bellingham, Washington