Wisconsin has these stupid noise laws, so I am now forced to add silencers to my Formula, 382 SR-1. It currently has 500hp's, but this fall I am planning on re-powering with 540's at about 630 hp.
My question is what is a good choice for silencers. I am not looking for the wanna be input. I am looking for someone who's been there and done that.
Wisconsin doesn't allow cut outs, but I was toying with the idea of using switchable Hardin Cyclones with a linear actuator instead of the air cylinder to run at variable sound levels rather than ON or OFF.
I only have about 10.5 inches from the transom to my tie bar when the drives are up, so the silencers need to be pretty short.
I bought a pair of Drew Marine Shotguns just to try a set out, but I don't think they are going to cut it.
Any suggestions out there ?

What are the laws in Wisconsin ?? Illinois has 90 db at idle. Mine was 115 at idle and all I did was use 4" 90 degree air intake boots with about 7" of aluminized exhaust pipe to get it below the water and now I am at 89 db at idle. I have big HP motors.

My setup doesn't look the best but it only cost me 80 bucks !!!

Or you can spend $$$$$$ and have custom made turn downs made out of polished stainless.

Check with Elite Marine. He advertises here and can hook you up with either mufflers or turn downs.

Smitty

WI law is 85 dBa at idle at ten feet from the back of the boat.
I thought about using turn downs, but there is too much gear on the back of the boat. I have external hydraulic steering, and with the hoses and linkage, the turn downs would hit.
I LIKE the noise, unfortunately I am disturbing the fish, or something like that.
Hell, even the old folks in my marina say they like the way it sounds.

CMI Sound Eliminations

I just looked up WI and it's actually 86dB. Realistically, there isn't a muffler available that will get you to meet the law with twin big-blocks. The CMI's will probably get you close enough that the noise police will leave you alone.

Minnesota has an even tougher limit of 84dB, so I decided to go with a combination of mufflers and turn-downs, but had to relocate the tie-bar to clear everything.

can you trip the cops up by running one at a time???when there checking it,,,wouldnt one be a lot more quite???

All you need is a hidden kill switch. When you get pulled over and try to test you, you mysteriously "can't get the engine to start" and you can blame them for effing up your day.

Sorry, I mis quoted the WI law, it is 86 dB, and I agree, it is about impossible.
I would generally just ignore the regulation and take my chances, but after a long day on a hot sand bar, enjoying Jake Leinenkugles handy work, it just gives the river patrol a reason to smell my breath.
I guess I'll just pick a set, and call it good, legal or not.

I carry a set of the universal silencers just in case. I keep them in the boat so I can swap them out with a short section of 4" pipe if need be. I too like mine on the loud side but if i get in a pinch and the water nazis are nearby I can be close to legal in no time at all.

When I failed my local water patrols test, the first engine was 96.2db and with the second engine fired I was at 98.3db. I am around 104db without any silencing mufflers. Turndowns 4" into the water is the only way you will get close to 86db.

Remember a decibel is a logarithmic unit of measurement.