I have one of the Centek units on my boat and am very happy with it. Originally, the water was discharged under the hull. In an effort to remove excess through hulls, I redid the exhaust plumbing. Originally the exhaust gas teed with the engine exhaust and exited through the side with an 8" pipe. My repower engine only required a 4" exhaust. So I ran an 8" exhaust pipe from the back of the engine room out the transom. The bottom of the pipe is at water level. The propulsion engine, generator exhaust gas and water from the separator, all enter the 8" pipe in the engine room. The result is essentially no splashing as the water flows along the bottom of the pipe, and then exits the pipe without dropping. The generator exhaust goes through a lift muffler, the gas water seperator, 20' of hose / pipe with 3 sweep 90 degree turns before exiting the boat. At the exhaust pipe discharge, noise is all but non existent.
Ted