need 4 silencer,to fit for 4 1/2" pipe and can handle ca 750 HK blown engines.Used, Helm operated, anyone have for sale??
sorry for bad english

Try Drew Marine.( There is a web site he is in Spokane Washington). If I had to use any I would try these first. They look very simple, priced right, and not a lot to fuss with.

Turn down pipes work nicely, but aren't switchable.
You post 750HK, are we talking kilowatts or horse power?

hallo and thanks
I am talking 750 horse power
túrn down pips, ok, but they only work then the boat lie still or am I wrong here ??
regards

Yup, they only help when off plane.
Thanks for the horse power clarification.

Oki, Do you have any experience of that type of silencer?
Regards Göran