On Lake George, NY the limit is 90 DB, 1 meter off the transom. I know 2 guys who run the CMI mufflers on twin 500/525's and they ring up 90.1 on the meter. It would be less 10 feet behind the boat remember.

I don't understand why all the Harleys running around with straight pipes or such do not have to meet the db requirements from the "Noize Nazis" like us boaters, hell, all of our boats are built right here in the Good Ol' USA just like the Harleys??
I have heard about a few boat builders who will be looking into incorporating the "water chest" technology on their boats at idle. Same concept as Mercury's new transom mount hush systems for their blower motors!
"Necessity is the Mutha of Invention!!"

Best Regards,
Ray @ Raylar

Has anyone seen or completed a test of different mufflers on say a 500hp engine and layed it out in a spread sheet?