Keith,
Good advice.
Marina has about a 2 mile approach area that is no wake. That is where the local patrol hangs out.
I wonder if I could rig up a pressure switch to activate the flaps when the exhaust pressure gets to high.

i use gaffrig switchable on mine i put a pressure switch in the system and a red L.E.D light on the dash next to the switch so i know when they are closed because the red light is on

I have 4 of the Gaffrigs with pump If anyones interested. They are a clap on 4.5 I.D.

I'm interested in these also for my Baja 20 Outlaw. It has the standard Corsa non-switchable exhaust thru the transom with muffler tips. Would love some suggestions guys.