I have no idea if the motors are mounted in the same position, but note that my tips are quite close to the rubrail, and quite a bit higher than the gimbal of the drive.

Note that you have your orange "dots" located basically at the gimball height, which would mean the tips coming through the transom would be at the water line. I think you're going to find that is not the case. I'm thinking they are close to where mine are. Check to be sure. Hope this helps.

ER ...is a 29 ....just put it beside a 292 fast tech ....

I know , it's almost identical. But it's still called a 272
A few years ago when I still had my t/330s I got beat by a 29 Fountain with a single HP500. Back at the ramp I was parked next to him while tying down and realized my 272 SR1 was actually BIGGER than the 29 Fountain . Now minus two feet for his swim platform and 2 feet for th beek it's onlt 25 feet as measure in Formula feet. Now subtact 1200lbs for a big block and drive...it ain't no wonder he was able to nose me out............................................... .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. ............................................
but no more ....

Outlaw is right, I rebuilt my swim platform two years ago on a 242 back then and the exhaust is at the same height as the 311. I have one picture but no way to scan it, sorry. I would still measure several different ways to be sure but thats what it looks I to me. The actual holes are real close to the bottom of your name on the back of your boat about where you stand on the swim platform. Hope this makes sense and that it helps you. Propwash

I was making plans to do the same thing with my 272 (twins)
I have removed my silent thunder to repair it. (replace wood at transom mount surface. )

I had already cut out the baffle plates and it sounded better, but was going to extend the exhaust "hose" all the way to the silent thunder tips, fabricating a roudn to square interface bracket for the inside.

I found some corrogated marine exhuast hose that is quite cheap and was going to use it. But talking to my boat'n buddy ( while snowmobiling...Michigan is a great state...anyway.....) he said corrogated creates a lot of back pressure.

So I plan to look for some preformed smooth hose.with the needed offsets. ( straight on the inboard, and about 4" on teh outboards . On my twins the thru hulls exit out the transom clearly higher than the square tips. especially at ride height sitting in the water.

I feel this will add some sound to the exhaust, gain no power, but eliminate the weight of the water inside the silent thunder and the exhaust leaks at the transom.

so does anyone see an issue with doing this to a twin setup?

Ramb

Once you get your "round to rectangle" adaptors made up, they make a reasonably flexible smooth wet exhaust hose that should be able to make the bend. I saw it in either the West Marine or Boat US Catalog I think.

I used a smaller diameter of this hose for my exhaust plumbing and it amazed me how easiy it would make a tight bend. Worked great.

Well, I completed the project.
sounds good on the driveway. will splash on May 25 ( after the ice thaws here in Michigan ) actually our first boat club run on Lake michigan that day.

sounds good, similar to other boats with straight exhaust. louder than the silent thunder. We'll see how it sounds at load and rpm soon

engines really need some lumpy cams though

See my post for "thru thunder modification" for pics

Ramb

i took my silent thunder off my 271, then put stainless marine manifold and risers on, it is barking like a big dog now!

the difference in plane time on the boat is dramatically faster