Tracy - I ordered a spintech muffler this morning.  They have a 2 1/2 x 9 x 16" model.  Their 321 s/s models however run $350, so I stuck with a steel one($129), figuring it's life span probably will be short until some design changes obsoletes it. I hope to keep mine within the cowling, so aerodynamic shape doesn't play a big role.  The thinness actually should help cool it better and I plan to blow oil cooler air over it and out the side.
   How's tha trailer remodel business?  Watch out for that spray insulation, you ususally have to just cut it out of your hair it's so damn sticky.
Kevin Lane  Portland, OR
e-mail-> n3773@comcast.net