External Mufflers - opinions please
 

Well it looks as if the Wisconsin and Iowa DNR have followed suit with Minnesota and are stopping every boat that "looks" loud and doing the 86 dba test. I have been fortunate to avoid their rath but feel my day is coming. I am looking at Corsa external muffler tips, Corsa silenced tips, Eddie Marine silenced tips, and Drew Shotguns. The silenced tips are the cheapest, but do they work and do they rob HP. The Eddies have a steel wool baffle inside the tip and the Corsa's have some sort of Bi-directional baffles inside. The Corsa muffler tips and Drews are basically the same money and will clamp onto my existing tips. In the end, I need to get more quiet but don't want to loose any performance I realized with my engine upgrade. The engine is a 509 with a HP 500 cam and Lightning headers dumping straight out the back.

voodoo,
Sorry to hear that the "boys" have found their sound level meters.. Not good..
In Mich we have to meet 90dba at an idle. So a lot of guys just use turn down pipes. They hang in the water at idle, but are open when on plane. Still pretty load when up and running. I opted to go a different route. I mounted a pair of 4" Borla stainless mufflers on the outside of the transom. I can meet the 90dba, if they check it according to the procedure. The Borla is a straight thru muff with stainless steel wool around the inner pipes. I feel that any time you put something in the flow pattern it will kill horsepower. So some type of straight thru will be better. The type with baffles will hurt the breathing. Not sure if you can meet the 86dba with anything but silent choice type setup. I used to have cans on the back and down pipes and flaps inside that I operated with silent choice air cylinders. That worked pretty good for our laws here. The shot guns will take some of the bite off it, but not much. Your 86dba standard, is that a drive by deal or what..

good luck..


Dick

What I did on my last two boats was to install downturn 60 degree elboes instead of the mufflers. The downturns end about 4or5 inches below the water line when the boat is at no wake speed. I then drilled about 20 -1/4 inch holes on the side facing the transom to relieve the thump and it will be much quieter as long as the boat isn't on plane. And the best thing is that it doesn't reduce HP

with the pipes in the water at idle, don't you have to worry about water being sucked back in or reversion? I had thought about doing this. BTW the 86 DBA is at idle, 4ft. up and 4 ft. back from the transom. I have the Salisbury flappers on the ends of my current tips and the tips also have the valves inside to stop water from washing into the tips. Can you still use the Salisbury flappers if the pipes is under the water?

If you are only looking for low noise level when idling in and out of the marina? Then I would go with the shot guns. No air pumps, solinoids(sp),switches,etc. I always like to keep it simple stupid.

Voodoo,
my friend has run the down turns on his boats with several motors.. He has CMI pipes that are dry out to the transom then the down turns go over the whole pipe. and he has no problems with reversion.. This is a big inch motor close to 600" and roller cam. If you have to meet 86dba at 4'x4' you will have to do either silent choice or down turns.. The donkey dicks as they call them are simple and cheep and dont seem to steal any power. If you want to experiment.. use some PVC to set it up temp.. if it works order some pipes from someone.. CMI did my buddies..

Good luck

Dick

There were some Drew shotguns in the OSO classifieds.That is what I am running but as to date have not been stoped so I don't know if I would make it under the gun or not! :cool:

TEAGUE TCM 450;s is all I have to say :)

They are the best IMO.
they really take the bark out both open and closed.

I feel the drews are more of a visual 'see I have mufflers' kind of thing. Never heard much change of hte 2 boats I have seen them go on.
I kow alot of people have gone with the IMCO Mega mufflers with great success. They are HUGE and you can get them either in clamp on to your existing tips or complete bolt through hull.
Not sure about the hawkeyes down there but if they are going to copy MN and WI then anything switchable is not ok. Just need to know when to and not to switch the teagues :)
When I put mine in I left the Y-pipe but took out all the silent choice acuators and vavles. Cannot see the tips from inside.
Know several others on here that are real happy with the teagues also.
I personally do not like any of the mufflers that have the external valves and hoses.

Teague Tcm 450's are the way to go. I have them for over 1 year with no problems. They sound real quiet when you want them to be. I didn't notice any power loss when open. The down side is cutting 4 1/2" holes in your transom.

I just put on a set of Shotguns on my Pantera with a 525SC. It was pretty loud. Even the water patrol at LOTO thought so:D The Shotguns helped a LOT. I'm guessing it reduced idle and cruise Db by at least 10-15. I'm very happy with them. They also have some adjustability and are an easy install.

Late spring I purchased a set of used Shotguns, thanks Cord. I just installed them yesterday on a 502 with lightning headers. The lightnings are quite loud and while no one has bothered me yet, I plan to go to the Erie Islands and figured I better knock the noise down some. The Shotguns were an easy install and I was surprised at how much it changed the sound. It makes a noticable difference and no decrease in rpms. My wife loved the sound of the unmuffeled lightings and is a little unhappy but if it saves us from getting a ticket.......

I've used the Corsa silencer tips (6") on several motors up to about 600hp with great results. The're a work of art too. Mine have a 45 degree cut tip with the internal 'spring' baffle. Went to open tips several times on different motors and saw no difference.

I haven't got to hear any of them, but from what I've read, I would go with the Shotgun's.

I would go with some type of non-switchable muffler like the IMCO mega muffler available as clamp on or as tip.

Switchables are illegal is some states and maybe your state is next. How would you like to spend $1-2000 for switchable with installation anly to still get a ticket for passing the sound test but failing the 'non switchable' and having to pay the ticket and then re-do the mufflers. Do it right the first time and do it once.

I put Drew Shotguns on my HP500 carb motors and they made a noticeable difference at idle. They aren't very concerned in TN, but I just wanted to be the "good" neighbor so added them. They're simple and don't effect top end RPM at all.

I'm going to Sturgeon Bay, WI later this week. We'll see if they're out in force checking db's. I'll let you know if I get stopped.

Switchables are illegal in WI. I boat along the WI, IA, IL borders. I think I will try the under water method first. I plan to sell the boat in August as my wife is going back to school. I hate to spend another 500-1000 for something I'll only need for 1-2 months.

If you get a set of Shotguns, you only need to drill one small hole in your existing tips to mount them. Then if you sell the boat, you can give the buyer the option to keep/buy them or you can take them off and sell them.

I have a Whipplechargered 502 Mag with Corsa silent choice. In NY we have a 90db rule at idle. I installed Corsa clamp on external mufflers and have seen no decrease in performance. Mine are not visable since they are under the swim platform.

NY also has a no cut-out rule. However, as long as your boat meets the requirement EITHER way, you will not have a problem(in court, if not on the water).

I knew that moment was immortalized. Just waiting to see when you were going to post the pic. You usually wait for just the right moment.
Actually though, I just put the Shotguns on last week. What a difference at idle and up through 4000rpms. You can really here the blower whining now and can actually hear what somebody else is saying in the seat next to you at cruise speed.

Can you use Shotgun's with a completely dry exhaust system? My water dumps over the side...

If you have dry exhaust all the available "boat" style mufflers will be quite a bit noisier. I have Gil full-time clamp-ons, which I ran on the prior dry Gill exhaust and on the current wet Lightning's (water enters at the transom just before the tips, about 4 feet from the cylinder heads).

The same mufflers with the mixed water are much quieter in "perceived" noise. I havn't put the sound meter on them with the mixed exhaust, but they were 106 db at idle with the dry exhaust (about 3 feet behind the transom).

If you run dry exhaust I'd look at the Borla/car style muffler solution that Dick (Mr Gadgets) mentions above.

-Greg

Can you install Shotguns on short tips. I only have about 1 1/2" past the flange to work with. Utah is starting to crack down as well - buddy got a $1000.00 fix it ticket last weekend and he was only 2 Dbs over- Ouch!! :mad:

Yes, I think you need less than an inch. They just slip over the existing tips and then drill a couple small holes and bolt them on.

I run the Shotguns combined with internal baffles on a 330hp 454. Both bolt on from the outside. I think the baffles are Eddie Marine. They cut the diameter down to about 3" on a 4" exhuast. I lose about 50-75rpm. The Shotguns alone do not do much. Fortunatly, my exhuast tip are angled down and half under water at idle. With the shotguns, the exhuast exists completely under water at off plane speed. You can adjust the Shotguns so that they do not open all the way as well. A nice feature if your taking the family or inlaws for a quite ride.

What about slip in silencers? I know cp performance and rex sells them. I think they are about $100. per pair....If i remember they reduced8-12db on a 500hp motor. With very compareable power loss. Very easy install and are considered "permenent" But they bolt into your tips and can be taken out in about 5 minutes if need be. Also because of their design they help with reversion problems.....

"Bad-Habit"

I ran a pair of those CP Performance slip ins. Lost 3 mph on the top end and could barely hear the motor run at idle. Took them out after one run. I now run the Drew Shotguns. Have for 4 years. Have NEVER been pulled over. I have wired them all the way open a few times (they rattle a bit at idle) when trouble shooting (to eliminate the noise). Believe me, they DO take the bark out of exhaust noise. I've never db'ed my moter, but I KNOW that at idle, with them open, I'm quite a bit louder than 90 db (the limit here in Michigan). A few weekends ago I happend to pass right by a marine patrol officer on Mona Lake, probably 15 feet from him at 900 rpm. He smiled and waved. Later that day I ran into the same officer at Taco Bell (yo quiero Taco Bell!!!!). I asked him point blank if he thought I was too loud. He said no, he wouldn't bother me becuase I was not noticably loud. I'm running over 400 hp thru EMI manifolds with the tips under my swim platform, which is teak and slotted.

I think the key to not getting pulled over is to make sure the boat you are next to is louder than yours!!!!!!!!

If you are running an Alpha or Bravo you can run the external clamp ons, such as the gil's, and put in silent choice type pipes. When the valves are open, the exhaust can exit through both the drive and the tips. The drive exhaust pipe also acts as a type of crossover and that also helps drop the backpressure. This has been tested and I wouldn't run clamp on or slip in mufflers without also using the prop exhaust too. You don't even need the cutouts and in Wisconsin if you have the cutouts before the mufflers (and it passes the tests with the cutouts open) it's legal. You are using the thru hub exhaust to bleed off the extra backpressure.