Quieter exhaust?

[cadunkle]

I have an '89 Saltare which has a 454 and straight pipes, too loud. I'd like to quiet it down. I first looked for SuperTrapps as they were factory on earlier boats but are NLA unless you can find NOS. Given that I see two options:

One is the common fiberglass ski boat mufflers. None I've seen give a decibel reduction. Anything is better than nothing, but installing these would require cutting the floor and glassing in new wood so I'd rather not do that for an unknown change. I also see many threads mentioning these blowing out or cracking causing leaks, not great for anything at or below the water line.

Another is transom mount mufflers, such as Hardin Marine offers (https://www.hardin-marine.com/p-1260...silencers.aspx). Theses claim 8-10 db reduction, or about half as loud. They're also compact and should be an easy install after getting the gas tank out of the way. I'm leaning towards trying these first and if still too loud I'll put the long ski boat mufflers in front of them.

What options do you guys recommend or have tried to quiet down your boats?

[cadunkle]

I ordered the Hardin Marine transom mount silencers (https://www.cpperformance.com/p-1259...silencers.aspx). I was worried about the flange size and whether it will fit inside the recessed part of the hull. My exhaust tips are 3" and these require a 4" hole, so I'll have to drill out to 4". I was worried about the flange size fitting in the recess around the exhaust tips, but the flange it 6" OD which will fit with a little room to spare.

After ordering I realized my risers have a 3.5" outlet, so it may have been more prudent to order 3.5" inlet transom mufflers and just get the 3.5" in/out ski boat mufflers as well tomaximize noise reduction while minimizing impact on performance. Realistically at marginally more power than the stock 330 HP I don't expect an appreciable difference in power. I've run 450 HP big blocks in cars through dual 2.5" exhaust, so 3" should be fine for a wet exhaust. The factory pyramid manifolds and risers are probably more of a restriction than dual 3" exhaust with mufflers. I'll see how these do and hopefully I don't have to tear up the floor and install the long ski boat mufflers.

[Salty87]

Why no FAE type solution?

[cadunkle]

I have heard mixed reviews about the effect on the wake. I've not ruled out FAE, but it will be a last resort for me. The transom mufflers arrived today, so I should be able to get them installed this weekend.They seem like quality parts and have an internal flapper. I'll add a flapper on the end as well which should dampen noise somewhat from my experience with exhaust being noticeably louder when I had a flapper tear off. There is a .075" gap between the OD at each end of the muffler insert and the ID of the tip though. I may try to flare the inserts to fit more tightly in the tip and use a sealant on them. I'm cautiously optimistic, but suspect I'll be adding ski boat mufflers as well. I doubt that would be inadequate, but if so I'll try FAE at that point.

[Jetlink]

Refresh my memory here Cadunkle, you primarily wakeboard behind your boat right? Are you talking about the resonating exhaust noise out the back or does it carry into the boat?

[cadunkle]

Yes, primary wakeboard and kneeboard. It's too loud both in the boat and behind it.

I got the Hardin Marine tips installed today. The factory hole was 3.25", which I enlarged to 4" by using a 3.25" hole saw inside the 4" hole saw to serve as a guide. The existing hoses were the perfect length to get two clamps on each end. The original install has two clamps on the stainless straight pipe and one clamp on the tip. The original tips were plastic and had melted a fair amount. They also came right off with zero effort after loosening the clamp and removing the six screws. My bilge was dry for a couple years after replacing the rudder and resealing the platform brackets, but these must have started leaking.I don't feel so bad however this turns out as apparently it needed to be done anyway. I sealed the new tips with 4200 fast cure on the flange and smeared on the pipe and in the hole in the transom. Screws are #12 x 1" long, I reused the factory screws. The transom is about 1" thick toward the top of the exhaust hole and 1.25" towards the bottom.

It won't be indicative of noise level in use, but I'll fire it up tomorrow in the driveway without the inserts and measure decibels at idle then install the inserts and measure again. If weather and other factors work out I'll take it out Sunday and get my subjective impression of noise reduction as well as measure decibels in the boat at idle and at speed.