"Roger Halstead" wrote in message
...
Mufflers can not be very effective on big engines without causing back
pressure and a reduction in power.

What you see in Europe is gained more by the reduction in RPM than the
muffler. Lower RPM, less output gasses means the engine is quieter
and it is easier to muffle. It is also developing less HP and in my
opinion creates a safety concern.

Not necessarily. The mufflers/silencers don't. Or don't have to. And
the quietest engines are the Rotax 912s which run at over 5000 rpm.
Of course they don't produce 260hp!

http://www.hliese.de/International/international.html

They do one for the Bo. They claim no performance degredation
and a weight of 2lbs.

"Beech-33, -35 und -36 ( all Versions with Conti. IO-520 )"

Paul