"Henry:
That sounds more li
"Henry:
That sounds more like what a "Y" is used for, if you have one muffler for each engine. Think of it as an open 4 and it's mirror image. 3" inlet, 3" inlet, and a single 4" outlet, to the muffler.
Rich's suggestion is what I did when I redid my engines and exhaust systems. I also opened it up as the elbows I got had 4" outlets. Turned out to be fine as the muffler had a reducer in it (salisbury's 5"+ diameter). All I had to do was add the stubs at the transom.
The elbows are easy to make, just use three pieces instead of two (extra cuts but works better). I wrapped mine with two layers of epoxy soaked cloth. You can also make the "Y" pipes but that takes the appropriate sized hole saw and a half round file. Again, two wraps of cloth was plenty.
You can also them pre-made if you rather not fool with it. I found the 10' lengths were priced in the reasonable range. They will last forever if you meet two criteria: 1) the cooling water needs to flow thru continually (just like the hose) and 2) you need to mount them securely so they don't vibrate (and wear thru). They can be joined with hose and clamps, just like Rich stated. I used mostly tubing and used the hose for the interconnects. You will also need hose for the initial 18" coming off the elbows."
