What do you think of my new muffling system? The tubes are 4". I'm having them polished now and when I get them back and test fit, I plan on angle cutting the tips. The tubes will be approx. 6" under water with the boat at rest.
I'm hoping that having all the tubes between the drives and pointed downward, the sound, @ cruise, will be absorbed by the water below. We will see.
I wlll keep you posted 0n how they work and will post the final pictures.

Gary, should be interesting. I thought I read about some Nor Techs or ? running similiar systems down in FL? Think it will have any effect on power to come on plane? Look forward to hearing how they work.

Any thought of connecting them or giving any additional support at the bottoms?

Gary,
Looks like that should quite it down. What did you use to cut the tubing?

Rick

The 2 outside tubes have tabs on the backside of ea. that are bolted to the swim platform. The 2 tubes, from ea. motor, are "tabbed" together 4" from the ends. If it looks as if I have to have more support , I will run braces from the bottom tabs to the transom.
I had to take the trim rams apart and insert a 3" sleeve to limit the "up" travel, so that the drives didn't crush the tubes upon full trim.

Your neighbours will be very happy and start to speak with you again !! LOL
I put the downtubes on my NT a month ago and am happy with the results. Kinda neat to hear the blowers whine. I am only into the water about 3" at idle. Better too long to start with. You can always shorten them if you like.
Have received many compliments at the marinas that I have gone into since.
Yes there are a couple of other threads that may be worth looking up on the subject.
Good luck
Bob

Gary, they look good! Down tubes are getting to be quit common in your neck of the woods. Let us know how they work.

The NorTech exhaust is all inside the engine compartment.
Both right and left banks meet at a single outlet the exits the transom ahead of the out drive and in line with the prop.
Merc claims the twin 1075's suffered no loss in power with this system and it's super quiet.

I like the Not-tech idea, but. If it is done the way that I'm thinking, they connect the the 2 exhaust pipes into a "y" @ the transom and use a hose or possibably an 0-ring, of some sort, (silicone i.e. hi temp) to connect the exhaust to the thru-hull exhaust exit.
My only concern, if it is done that way, is what happens if you loose a sea-pump, i.e. water in the exhaust to cool the system and the hose/o-ring. Isn't the whole exhaust going to get exceedingly hot, toast the hose/o-ring and let outside water into the engine compt?
I havn't seen how theirs works, i'm only theorizing. Any help?