I removed my silent thunder box, seals between it and the transom were leaking water.
I wouldn't mind replacing it with mufflers, Corsa have several options, 5.5 inch ones are made for 502's
would they tone down a 502 somewhat.
The open exhaust sounds good but is too loud for cruising.

Anyone using them, any pics?

http://www.corsaperf.com/MarineCatal...Guide%2024.pdf

I was asking myself the same question, cops are tougher and tougher on noise here... I doubt it would quiet down enough to reach the popular 90 db at idle... my formula has 92 db at idle thru the silent thunder platform...

curious to read the answers...

I have run into the same issue on a 2006 Formula that I built a couple motors for, they were not leaking but that is a lot of extra weight to be hauling around. I ditched the fiberglass box under the swim step and added Gibson tips to the tail pipes. The boat runs in Lake Tahoe (The most stringent noise law in the country) every summer and has not ever been pulled over. A pair of 6.2 Mercs with Whipples produces 89 decibels on my meter. And if you are running more horsepower, I used the Gibson turndowns on two Fountains running 1075s this summer with success, when you are off plane around the marinas your boat runs about 83 DB. If you use the turn downs make sure you have them fitted or you will load up the plugs. When you get on plane you will hit 98 DB or so.

are these the ones you mean
http://www.gibsonmarine.com/powertip1.html

any installed pics

what about water back flow,
do these have built in flappers or a design that prevents back flow

Formula is using Corsa Mufflers for Boats built for Europe

They have no loss in HP and sound nice but not too laud

thanx for the pics, have you has the oppurtunity to compare sound levels for mufflers to silent thunder?

My boat came with the corsa mufflers and captains call, so I am thinking about taking the mufflers off this winter and putting tips on. I don't think mine needs both mufflers and captains call. Any way I may have a set of four to sell if anybody wants them.

Dave,

Email me directly at [email protected].

My PM box is full. Thanks.

Sorry Bowen, I just tried to e-mail you but I have a government E-mail and it makes me jump through hoops and it would not go. Try to e-mail me I can receive them.
[email protected].

i'll take 2 if available.