J&A Engineering sells a Pitts style muffler for the BME 50 & BME 44. It is actually the same muffler and will fit both. As a matter of fact you can buy these mufflers direct from BME if you wish. Skip is correct as well, in that you can get the Banjo type mulffers.

As for mounting options, there are two that come to mind immediately: Hangar 9 beam mount (aluminum),

[link=http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=HAN2033]http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=HAN2033[/link]

And the Great Planes mount,

[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXATG7&P=0]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXATG7&P=0[/link]

Hope this helps.