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View Full Version : Conversion from Silent Master to Dual Exhaust??


chrisbank
03-31-2008, 10:38 AM
I have a 91 Prostar with Silent Master exhaust-

Has anyone ever converted their boat from Silent Master back to straight dual exhaust with mufflers beneath the floorboards?

TMCNo1
03-31-2008, 10:43 AM
I have a 91 Prostar with Silent Master exhaust-

Has anyone ever converted their boat from Silent Master back to straight dual exhaust with mufflers beneath the floorboards?

I have helped convert a 1990 MariStar 210 over. You have plenty rubber pipe, just inset a pair of MC SilentMaster mufflers from MC or here, http://www.skidim.com/prodinfo.asp?number=NPNMS-030-1000 , in with 8 new clamps and IIRC 4 additional hangers and you'll even have some rubber hose left over. There was no difference in sound, but the cracked/leaking crossflow muffler was eliminated.

Prostar Rich
03-31-2008, 12:00 PM
Or just use exhaust hose from DIM and eliminate the mufflers all together. Much cheaper than buying two mufflers.

Prostar Rich

chrisbank
04-01-2008, 12:02 PM
So you are saying just run exhaust hose from the manifolds straight back to the rear of the boat?

454Prostar190
04-01-2008, 12:34 PM
It will rumble pretty good too! My S and S has no mufflers and at times you can hear it before you see it!

Prostar Rich
04-01-2008, 01:24 PM
So you are saying just run exhaust hose from the manifolds straight back to the rear of the boat?

What I did was I cut the elbows off of the silent master exhaust. I then ran exhaust hose from the manifolds down to just about the floor. Used the elbows I cut off and then connected to the existing exhaust hose. I used the elbows so I wouldn't have a hard bend in the exhaust hose. You may not need the elbows if the bend is gradual. Make sure you use two band clamps per fitting. The boat will be slightly louder but not objectionable. Much less $$ then shelling out for two mufflers.

Prostar Rich

chrisbank
04-01-2008, 02:41 PM
Sounds good -
I think it needs to happen.
Thanks for the info!

H20skeefreek
04-01-2008, 02:48 PM
IMHO, that will be obnoxiously loud.

wakeX2wake
04-01-2008, 02:59 PM
IMHO, that will be obnoxiously loud.

kind of what i was thinking... i want it quiet

Prostar Rich
04-01-2008, 04:18 PM
IMHO, that will be obnoxiously loud.


Have you heard a MC with out the muffler/mufflers? I have and it is not obnoxiously loud. I have done this set up to my boat and it sounds good and was an easy fix for a leaking silent master muffler. The I/O's with thru hull exhaust are obnoxiously loud and my boat doesn't even come close.

Save yourself the $$ on the mufflers and get some exhaust hose.

Prostar Rich

flipper
04-01-2008, 04:22 PM
I've herd M/Cs with out mufflers, and like the sound. They are loud, but not all that loud. Certainly no where near the noise of the strait pipe jet boats.

chrisbank
04-01-2008, 05:51 PM
We are on a decent lake - noise is not a concern.
I like the rumble of somewhat straight exhaust - and think that it should not be obnoxiously loud.

H20skeefreek
04-01-2008, 08:02 PM
I've heard my boat and it has the straight fiberglass mufflers, and it is borderline obnoxious. I'd prefer it be MUCH quieter....that's why I said IMHO though.

And to compare it to a jet boat that is SUPPOSED to be obnoxiously loud by the owners design doesn't really mean much.

Lottawatta
04-03-2008, 09:51 AM
I have a 91 Prostar with Silent Master exhaust-

Has anyone ever converted their boat from Silent Master back to straight dual exhaust with mufflers beneath the floorboards?

I have a 91 with straight exhaust. No muffler at all. Very little difference at idle - Some difference in the sound when at speed, but no lounder than the wind noise and you are still able to talk over the motor noise - Somewhat of a growl when behind the boat, but no louder than the Malibus are - from the bank, you hear the rumble when it goes by, but not nearly as loud as a Harley going by on the street. It certainly is not obnoxious in my opinion, but to each his own.

What is the difference between the silent master vs. under floor mufflers other than size and location? I would think backpressure and sound would be nearly the same with either one. If you are looking for sound, go with straight exhaust.

johkur
04-03-2008, 11:03 AM
Here's what the new silencer tips look like instead of using a Silentmaster. It was in a new 2008 L18 (that I expected a silentmaster in based on the website). I'm told that MC believes its about 2-3 db louder than the silentmaster, and that it makes a lower frequency rumble that makes it more obnoxious that what 2-3db would normally do. Of course 2-3db at the higher engine levels is a huge difference anyway. But if this piece is 2-3db louder, and its probably making a big difference versus straight pipes, you're definitely going to have a much louder boat. If you're goal is noise, you're going to get it. But if your goal is to get the silentmaster out of your way, I'd recommend considering items like http://www.rexmar.com/page237.html which appear to be similar to what I saw in the X45L18, photo attached.

chrisbank
04-03-2008, 11:38 AM
Thanks LottaWatta - I like the idea of a little rumble without being obnoxious. As long as the backpressure ect is fine I'm going to get some exhaust hose and get to it!!

I have a 91 with straight exhaust. No muffler at all. Very little difference at idle - Some difference in the sound when at speed, but no lounder than the wind noise and you are still able to talk over the motor noise - Somewhat of a growl when behind the boat, but no louder than the Malibus are - from the bank, you hear the rumble when it goes by, but not nearly as loud as a Harley going by on the street. It certainly is not obnoxious in my opinion, but to each his own.

zekedog
06-12-2010, 05:08 PM
I just cut the Silent Master out of my 92 PS190 because it was leaking badly. Saw zaw about 3 inches above where the pipes come up from the bilge area. Removed the riser hoses. Picked up 3 ft of 3in marine exhaust hose from my local marina. They had a piece laying around and gave it to me for free. Wrestled the new sections on. Used the old clamps. Took it to the water. When it fired up it startled me because it sounded a little pissed off. While idling out of the marina the girl in the back couldn't hear a word I was saying unless I yelled. Underway I could carry on a conversation with the passenger but the people in the back could have been 100 yards away. They said it was loud. I changed places and tried the back seat. Sounded like a NASCAR race under the swim platform. I asked a fisherman while idling in if he was having any luck. He didn't hear me. My "doghouse" does need new insulation so that might help some. Have to see how many complaints I get when there are more boaters out. May have to buy another muffler. It did sound good in my opinion. Fisherman don't like me much anyway.

TayMC197
06-13-2010, 10:16 AM
Kyle just made the conversion on his boat (93 190) a few months back. I was in it all weekend at broken bow and it wasn't honestly that much louder. Sounds really good IMHO. All he did was removed the silence master and put 2 schedule 40 pvc pipes in between and connected them up. He now has the option of putting it back in if he needs. I don't think its as loud as the 87-90 models but sounds really good.