I would say it is certainly rare to get MAJOR CO2 poisoning (pass out or death) but minor side effects are very common! Headache, nausea after day on boat.
There is no plastic, it's all stainless steel, all hand welded and powdercoated. They are currently $50 off so about $420.
From their website:
My boat has an "Ultra Low Emissions" engine. Is there still a risk of CO poisoning?
The Ultra Low Emissions standards do NOT cover Carbon Monoxide. So far, we have only conducted a brief test of CO concentrations behind an Ultra Low Emissions rated boat and the CO concentrations appeared to be as high as any other inboard boat that we've tested. If you have an Ultra Low Emissions boat, do not be lulled into a false sense of security; your engine still produces lethal levels of CO.
My downpipe is backwards in this pic.