Replaced my Volvo muffler with a cheapo plastic job purchased from my favourite chandler for around £60 about a year and a half back. It works a treat with no hiccups throughout the 60 hours or so of engine running time so far. It was significantly cheaper than a plastic Vetus too, and did the job without need for an additional silencing device. Out of concern about whether going plastic rather than remaining with an expensive part stainless steel and part rubber Volvo silencer might be a step into the unknown, I fitted a NASA Exhaust Temperature Monitor. Over the last year or so since the monitor was fitted, I have not seen exhaust temperatures higher than some 28C to 30C, though this is obviously much dependant on sea temperature and an adequate flow of cooling water from the sea inlet in the saildrive which can get clogged by mussels and other undesirables.
