Switchable exhaust that passes sound test either way?
Adjustable exhaust systems are an expensive option that can add several thousand dollars to the price of a boat.
How many people do you think would spend that money on a system that would not exceed legal sound level limit in the open position?
That would be like buying an option on a car that would allow 45 mph top speed adjustable to 65mph top speed.
Those that say they want adjustable exhaust to make the boat quiet are fooling nobody. They want it to make the boat loud. If they really wanted quiet, they would choose a boat with through the prop exhaust. If they want mellow, then they could choose through hull with
GOOD mufflers.