On another note, running all the hot exhaust down thru your outdrive is not doing it any good. You can tell a drive that has all of exhaust going thru it vs one that has not.

I have never heard that before???

I have been told there is a back pressure issue and the silent choice system is not designed to remove the volume at RPMs above 2500. I am sure there is a safety factor in the number but I have not tried it.

There we go at least I am not the only one. wel i tried it at 3000 and it worked.

I have heard no more then 3000 with them closed

Oh i did not know there was a problem with runnning them closed at wot, just closing them. I ran mine at wot and they stayed closed

What about at initial start up of the engines? Open/closed or it doesn't matter?

I think it depends on the engines, something small like a 350, you can run them closed, but I am pretty sure anything bigger and you should not run through the hub past 3000. also I heard that it is not good to switch it while running

I am running a 540 with silent choice exhaust. I cant and dont run with mine closed above 3000 rpm. One thing i had to do is add water to the exhaust behind the flaps so the heat from the exhaust that would slip by the flaps wouldnt melt the rubber couplers. Works great, and gets the water police off my arse. Its great to have a big motor and not freak out the kids when i pull them on tubes! The only downside that i have experienced is that my cam couldnt have any more that 230 deration in fear of having water reversion when the exhaust is closed mainly at idle. Gave up some hp but its well worth it.

Oh i forgot to mention, I had no less than 1/2 dozzen marine engine people tell me that i could NOT use my silent choice exhaust AT ALL with the 540.