I have a 86 Bahner 21' with a Berkeley jet and BBC 454. Just got the engine back from a rebuild and would like to install an exhaust diverter system while I'm putting it back in. I like to hear my radio when I'm idling around the marina. The above the water line transom exhaust is pretty loud.
I purchased some used, solenoid actuated, exhaust diverter valves that are kind of a Y configuration. Coming off my logs and snails is a 4" exhaust hose that heads out the back transom above the water line to the exhaust tips with flaps. I have enough room to splice in the diverters and run a 3" hose below the boat but I'm concerned about that and don't want my boat on the bottom of the river or blow my motor by pumping it full of water. Also wondering what tips to use if this isn't a stupid idea. Something about drilling 3" holes in the bottom of the boat doesn't feel right.
Is this a bad idea? Anyone have any experience with this?