Fishan, that answers my last 2 questions, hope to cut my holes this weekend.
Thank you for the help.

Hey! I just made an account here so I can contact you. Your exhaust work came out awesome on your formula, did you remove the swim platform to do it?

Hello I'm new to the site I have a 1990 formula 357 sr1 I'm looking to customize my silent thunder platform it off the boat looking to keep the swim platform and chanel the through the swim platform with the exhust and keep the ariginal rectangular tall and flaps any pics or ideas please share

A few people have completed the modification on here, more recently TomZ was going to install this same setup on his old 242. Move over to the Formula section and post there, you may get more of a response. I was going to do the same thing you were thinking but ended up leaving the ST off the boat and installing an aluminum swim platform.

looking to modify my silent thunder exhaust it is just way to SILENT and no thunder !!!! i under stand that people are gutting the baffles and drilling holes ....are you able to do that with the swim platform on if not how much of a pain is it to remove the platform

What model Formula do you have? The modification can be done without removing the platform. My 292 has all the baffles removed and the rectangle ports enlarged in the rear. The ports were enlarged by removing the existing trim ring/flapper assembly and cut larger rectangles out then installed a metal rectangle trim ring that I cut from a piece of stainless. Really changes the sound of the boat with those minor modifications. Others also drill holes in the bottom of the platform with a hole saw to allow the water to drain faster, this is done with a hole saw. The baffles can be knocked out through the rectangle ports by drilling holes around the perimeter and hitting with a hammer. Let me know if you need any more help or clarification. I can text you pictures when i get home if you DM me your #.

I just did this mod about a month ago, just used a long drill bit to drill holesin the top two corners of the baffle and a 12" blade on sawzawl to cut inbetween. probably cut about 80-90% of the baffle plate off. most tedious part is unbolting the factory exhaust tips and flappers. smaller hands would have gone long way for sure!

Build a snarky engine, you will hear it fine.
My high-ish compression 383 with big-ish cam and long tube risers is so loud i have to quiet it down.
I don't think my platform is very silent. Though it was a lot quieter with the OE 350 Mag.

i did the mod myself last year and found that putting a dab of super glue on the nut, then stickin it to the fiberglass holds it there just enough to get the bolt threads started. obviously don't get glue in the threads. once i did this on the second tip, it took a fraction of the time compared to the first side i struggled with to get it buttoned back up.

but having the baffles cut out is how the boat should have sounded from the factory. i even took the rubber flaps off the tips and that really made the difference... at idle it sounds 100% better, with a big, deep, smooth, rumble, but no/hardly any sound increase under power.