Before you bash, I have read the other threads and still can't decide which way to go. I have blown 540's with 4.5" dry stacks (EMI's) that are too loud in some areas that I boat so I need to do something about the noise. Doesn't have to be full time but I need something at idle. I don't need a Cadillac but even going to eat attracts the wrong attention. Yes, I know I'm getting old.

I've looked at the options for some time & need some input. Keep in mind that I have a 38 Fountain. The exhaust at idle is just above the water line.

Here's my take on the options.

Turn downs - I have read about reversion issues with turn downs but that enlarging the relief hole may help. If I went this way, the relief hole will be underwater on the Fountain. Any thoughts about relocating it & enlarging? I think it might work.

GGB - I have heard a lot of good things but they haven't returned my calls I've resorted to emailing them - we'll see.

Slip-on/transom mounted cans would be underwater at idle due to the angle of the exhaust at idle. I'm not sure that this would make a difference or create a potential reversion issue as there is no relief hole unless I drill the can.

Are there any 4.5 slip-ins that are worth looking at? I doubt that with dry stacks they would be very effective. Almost everything I have found is 4".

I would consider other options - toss them out & thanks for the help.

I think turn downs are the best way to go. Quiet at idle and no wake, and normal while underway. You will have no reversion issues as long as you are not backing up at like 10 mph

Some have reported water spray soaking the sunpad when running turndowns. I'm looking for a clamp-on solution as well.

cmi sound eliminators,,i heard you can put weaker springs in them to make them a little louder at idle..

http://www.youtube.com/watch?v=ZX0sVVShGc4

sunpad isn't an issue but reversion w/ dry stacks is & I don't believe having cans under H2O is the answer but idk.

I am running Borla mufflers, car type. 6" can with 4" in/out, with Shotguns on the end. The angle is downward and they do drag in the water. Never had a problem with reversion.. Dry exhaust, and I believe they are available in 4.5". Just checked Summit and Borla. No listing of a 4.5". But you could call them and check to see what they have.
My boat is considered quiet, but I can still hear the rumble and it still makes noise on plane. But people tell me it takes the bark out.
I would rather be stealth at 100mph. If they cant hear you, they may not see you..

This works great. Custom tailpipes on my 38 Cigarette with 1100hp. PSI supercharged blower motors. Nice and quiet at idle and because they exit between the drives and point downward, they are quiet from the side when on plane.

Is there much water spray at idle? How far below the surface (not including angle cut) do the pipes extend in that picture?

Looks nice...

The tips are angle cut at the ends and they extend approx. 6" below the water line when the boat is at rest. There are no issues with starting the engines with the tips as you see them. There is a "gurgle" at idle, and I have not noticed any water spray. The bottom of my swim platform stays a whole lot cleaner with the exhaust in this configuration, than when I ran the pipes straight out of the transom.

This is the way it used to look before the "new" tailpipes