Has anyone ever scratch made a quiet muffler for a nitro engine. It seems you can't buy a muffler that doesn't make a lot of racket. I know motor vehicles can be made quiet so why not nitro engines? I have the tooling (lathe, milling machine, etc) to be able to manufacture one. I wonder if you made the outlet pipe a bigger diameter increased the size of the muffler itself and baffled it would that work? How much back pressure does one really need? Has anyone experimented with this before?

Hmmm...I have purchased and used a number of mufflers in the past that only read only 84db at 3 meters (9 feet). That is considered to be relatively very quiet. And a number of them where also relatively inexpensive.

I have a Rapter 30 with a nice running OS engine, the muffler on it is quiet at idle but that changes once the RPM goes up. What was a good muffler in your opinion Syclic?

Here are the two I have used on an OS-37 that read 84 db @ 9 feet in the hover at 1700 rpm and that produce very good power while leaving the needle settyings very user friendly

1 - the Century CN3037 - surprisingly good for its low price (around $40.00)

2 - the KSJ #1545 - though it measures the same on the SPL meter and prvided the same power, it did sound a bit more mellow (around $80.00)