Mine are CMI , and I have a switch that I can close them but I thought it was for noise reduction

muffs
 

i have two sets of 4" gaffrig mufflers w/ a rebuilt pump
like new cond.
pm me

goin down on the 15th to pick it up. Spend one week on the gulf then will have it home in WCL.

nice... call me, ill let you take me out to lunch, and let you take me for a ride.......:p

Here are the turn-downs that I had on my boat. They are for 4.5" exhaust.

$500.00 plus shipping gets'em:party-smiley-004:

More

Today I recieved an email from the ex owner of my boat :

Hi Michele,
you have the flaps inside the mufflers and you want to add flaps on the outside ?
I think, its to much backpressure for the engines, they will runing to hot and will not have the full power !!!
Dont do this, the mufflers are enough !!!
as you can see on the picture you sended me, the flaps are fixed on an exhaust pipe and not on a muffler !
Belive me, flaps and mufflers are to much for the engines.Try to go full thottle with the mufflers closed, you will loose about 300 RPM and the engines are running to hot.
Greetings
Kurt

What do You think ?? Is he right ??
The only thing..it's I'm a little bit scared from the waves that we have in our seas....and the risers are not so high .....



Mike

I had the internal muffler flaps on a 96 Topun and they let water in to ruin a motor. Mercury as well as TNT told me that the outer rubber flappers are the way to go to play it safe.

I've bought 4 @ Phil yesterday ! :D

Kurt is right....you don't want to run the CMI switchables in the closed position at high rpms....once you are going to idle or float awhile you can close them....