This is the first good data and muffler design
information we have had so far.
The peak db readings are correlating well with
what we are seeing with the Mazda.
A 20 db drop in noise is an excellent result.

If this muffler were 9 inches in diameter
and about 12 inches long it would have 800 cubic
inches. A slight variation would be 8.5 inches
in diameter and 14 inches long. Both should fit
in most cowls. OMC blasted air at the exhaust
pipes coming out of the engine with the main cooling
blower to keep them cool. A blast tube or electric fan
could be used instead.