Subject: Loud boats
From: "Doug Kanter"

I'm using the term "speedboats" to describe boats which sound like they have
(and probably do have) a pair of 400+ cubic inch motors in the back?
In
order to achieve their purpose (speed), is it absolutely necessary for them
to be as noisy as they are,

Not necessarily. But exhaust restrictions can lower max horse power.

or are they just designed that way, in the same
way some morons alter their motorcycles because "loud pipes save lives"?

In some cases yes. Except for the "save lives" part.

And, when they're idling, why do they sound (and smell) as if the engines
are only firing on half their cylinders?

Cam timing and lift patterns.

Capt. Bill