It ruins the diverters. They are not designed to handle that much exhaust pressure.

A single engine stock 454 with wet exhaust is not over any legal decibel limits.

+1 with Griff. I believe it may also state the same in the owners manual.

I've been told to never to run over 3k rpms as well.

Usually the noise limit is measured at idle, not while on plane. Don't know your lake, but testing is always done at idle and where I boat I can be as loud as I want once on plane. Example - Turndowns are the preferred method of noise restriction and once on plane, the exhaust tips are out of the water making the boat pretty loud.

There is some confusion over whether switchable exhaust is even legal in NY, but personally, Ive never had a problem.

Yep, 3K RPMs is the max.

Am I the only one that thinks it would be a blessing for this to fail? This is one of the first things I ripped out of our boat.

A good friend of mine runs his closed all the time at high RPM to keep his wife happy. I keep telling him he's asking for trouble down the road. He refused to,listen to me. I found his owners manual and showed it to him in print.

Buck