Turndown exhaust
 

I did a search and didn't find anything useful.

Anyone using the Gibson or CMI turndowns (aka "DonkeyD1cks") and willing to share their experiences with them? I don't really dig the looks but I've got a couple of young children and the noise at idle and low speed seems to be excessive for them with my current exhaust (which I actually quite enjoy!).

Thanks!

Check with forum members "GLH" or "Old School".

Both of them have some time on sets I've sold them.


Fred

Thanks Fred. Will do.

We sell alot of them. I run them on my Pantera and Brad runs them on his MTI - see this months Extreme Boat!!!

They work great, are silent when idling and are open pipes when running.

If we can quote you a set, let me know. Pantera discount in effect! :D

The CMI Sound Elimination Mufflers are awesome also!!

Kirk

DS, For a slight reduction you can move the allen screw down one more hole on the Shotguns. It will help a little.

I had air activated mufflers on my 38 Cigarette w/1100's for several years and got nothing but a giant hassle from the water patrol.
I removed them and made a complete new exhaust from the transom. It goes underwater 6" at idle, shoots the exhaust down rather than back and at speed is all between the drives, which helps the noise factor from the side. It is now very quiet. I did drill a small hole in the bottom of ea. pipe, near the transom to relieve the pressure for start-up.
I wish that I would have thought of this years ago, it would have saved me a lot of money for noise tickets and mufflers.

RMPRam, that looks very trick. I think it's cool.

RMPRam, That is a fancy transom.

Subject to engine size, is there most back pressure on the outside banks ? The outside pipes are longer and have two elbows vs. one on the inside. One could wonder if there would be on imbalance.

Have you compared spark plug color and condition between the Port and Starboard heads ? Or, looked at each head with a temperature gun after a hard run ?

I have not done any checks on the outside plugs. I realize that the outer pipes are longer and contain one more sweeping right angle bend than the inner pipes but that was necessary to place the pipes between the drives. I'm running EGT probes on #6 cyl of both motors. That would place one probe on an outer bank,(stbd. motor), and the other on the inner bank. The result that I've seen, is the stbd. motor runs @ 1300 degrees @ speed and the port will run @ 1350. Does not seem to be any problem, so far.

Thanks for all the info! Next step is to see if they'll actually fit on my boat (it looks like there's a potential interference with steering rams).