i know there is a post here somewere about this
but i can't seem to find one
i have the corsa silent choice and when i winterize
and am sucking up the antifreeze should the exhaust
be opened or closed or does it matter--

I always left mine open but I don't think it matters. By the time the water gets to the diverters, I think gravity will let the water drain. The freeze issue is in the manifolds and risers, not the rest of the exhaust.

I keep mine closed, but I don't think it really matters. The upper pipes are angled downward slightly so any water is going to exit out the transom thru hull pipes. I'm not sure if any water gets caught in the lower bull horn exhaust pipes, but I take it through there so I can catch the antifreeze coming out the exhaust under the outer gimble and recirculate it back through the engine using a bilge pump in a catch bucket connected to ear muffs.

My friend runs his closed and lets the antifreeze mix run back into the tub until the thermostat opens and then flips the switch at the end to make sure some mix goes out the thru hull exhaust as we fog it.