Hi. Heard that a 496 mag ho needs open exhaust or silent choice due to the high power or you can burn your valves and the engine can run hot.
is this true?
i got a 496 mag ho in our cruiser and thought about remove the silent system.

Interesting claim...

Mercury says to never run your silent choice, closed, over 2600 rpm.

It requires the open sleeve at the transom exhaust flange. Make sure you do not have the full exhaust bellows that routes the exhaust thru the prop.

i have the "open" one so it will work?

its in my cruiser and use to be att 3200rpm most of the time. Never wot runs

cruiser boats route exhaust different ways and so forth but It sounds like you have a bravo 3 ?? twin engine boat ? if so then you will have the standard Y pipe and then thru the transom and out the open end sleeve ? Anyways put some pics up if needed or explain exactly what you have for exhaust and the set up / routing

im sorry
its a single engine boat with a bravo 3.
for now i have a silentchoice from mercury
and a standard y pipe through the transom and to the open sleeve.
And i want to remove the silentsystem and replace it with 4" "elbows" down to the y pipe.
And just wondered if this may couse trouble due to high resistance to the exhaustflow
couse i heard that the ho models need open exhaust at higher rpms