fischan what did you cut the holes with and how did you fill the gap around the tips and hole? where do i get new gaskets for silent thunder platform?

#1 - making it louder won't necessarily stop the Bajas from passing you. Louder does not always equal faster. Nothing is more offensive to me than a slow loud boat. If you make the noise, you better back it up with performance.

#2 - you have baffles in that Silent Thunder platform. It holds water in there so the exhaust has to burble thru it. Cut out the baffles, and half your battle is won. Also holesawing holes directly under the exhaust path about 3" off of the transom will dump the water and give you a freer flowing and louder exhaust. Most people use 2" diameter holes, but you can use whatever size or multiple holes. This method will let you start with a little hole and add more until you get what you're after - not something that you may regret later.

#3 - the rectangular outlets with rubber flappers is fine. No need to replace them with round unless you are just dead set on it.

#4 - yes, I've seen additional rectangular outlets used on the underside instead of open holes. Works pretty much the same as open holes.

MC

That is it. Exactly what i want to do.
Fishan
looks like you started with std platform, what was lurking inside platform?
Any mods to platform, stuff inside to be removed, modified, etc?
Did yours have the o-ring gaskets between platform and transom originally?
How did you handle the seal on the outside of platform?
How far out did the pipes extend beyond the platform?
How did you get the angle correct with the posterboard and get both of them the same?
Gmgearhead454,
did you get yours done?
Any pics?
What did you use?

Yes I finally finished it, I ended up removing it completely, filed the holes, painted the transom, and built a tubular aluminum one. Hard as hell cause of the angled transom, but turned out beautiful. I'm trying to post pics but I can NEVER get pics to post on this site for some reason....

So you completely ditched the formula platform?

Yup. I swear it makes it look 10 years newer. I'll get on my pc later and try to get some pics on here

To post pics easier:

Click on Forum Actions, then General Settings and turn off the Enhanced Image Uploader at the bottom of that page.

Thanks Griff, never saw that before. Still won't upload tho... I've tried from a PC and from my android... >:(

Are you seeing the "upload" button???? It is hidden way on the lower right side and isn't visible unless you scroll over or enlarge the window.

It was a silent thunder platform but I glassed in the rectangular holes. The seal on the outside is 3m 4200 uv resistant. At the top the tips measured something lik 1.5" away from the fiberglass, the bottom was like 4" if I recall correctly, it's been a long time since I thought about it. The angle was more eyeballed than anything, 15 years as a pipefitter/welder. Sold it August 2014.