need help running twin 350 400hp on 28-0 sonic emi thunder exhaust with stainless risers and silent choice.the boat is unbeliveable loud.the water temp on both motors 148 the risers are cool but you only see slight water dumping out.im running seawater pumps the drives are alpha with a block off to the motor the drive pumps are for cooling the drives only.any help on getting more water to quiet the noise.

When the exhaust is open at idle a lot of the water runs down the Y-pipe.

is that normal?

Yep!

sonic28,
Do you have a water bypass system onthe boat, you only need enough water going threw the exhaust to keep your hose connection from melting. Too much water
will rob you of horsepower. If you have a bypass system there will be 4 holes comming out of the transom. This system lets the proper amount of water to go into the exhaust the remaining amount goes to the bypass system. If its really to loud get some ear plugs an enjoy them horses.

no bypass just loud
thank you