Ed Anderson:    I recall (if memory can be trusted?) that you are using 304 stainless for your exhaust manifold.  I am wanting to make a tangential muffler for my 20B, and wonder if the following might last a reasonable time:  1.   From the ports;  2" x .150 wall
2.   Tangential tube;  4" x .120 wall
3.   Exhaust pipe;  2.5" x .120 wall
4.   End caps on tangential pipe;  .125 plate
5.   Center tube (to help swirl, and to reinforce end caps);  3/4" x .080 wall  (wondered if it would be a good or bad idea to run cool air through this to cool it and the exhaust a bit, or better to leave the ends closed??)

   Are these walls heavy enough to last?  Or is using $175 worth of 304 a waste of time and money compared to getting the more expensive 321 stainless?  Your opinion is most welcome.

Phil in IL