Gary wrote:
A week or so ago I asked about muffeling the exhaust on my boat.

One person (Dave) suggested:

You might be able to simply slide a baffle into the exhaust
outlet.
They are good for taking the rasp out of the exhaust note and they
are
simple to install (and remove if desired).

I've looked around a bit but haven't found any such devices. (Not
in-line
mufflers, but baffles that can just be "inserted" into the exhaust
outlet.

Anyone know where to find information on these?

Thanks,
Gary

Here are some for a Mustang, perhaps will give you ideas, although this
is a bypass, as opposed to something adjustable inline.