Paul,

   I am trying to get more information about this, but in the meantime I
   had to wonder why the exhaust was such a problem, since there are other
   20b's flying, to say nothing of 13's, that have evidently tamed their
   exhausts. Would it just have been because he was trying to fit it into a
   slender Mustang cowl?

   Peter G

   We have at least two RV4 tandem airplanes that have flown. I own one and
   the other was built by Brian Trubee.
   Brian's has an aluminum cowl. Mine has SS sheet between the exhaust and
   the fiber glass cowl.
   There is also a scale spitfire running in Texas.

   We have a bit of evidence that a too restrictive muffler will raise the
   EGT's above the normal 1600 to 1700 F.
   The secrete is to use thicker wall (.090") bends on the ports. Or even
   thicker .125".

   The mixture ratio enters into it of course.

   Here is  our latest muffler recommendations.
   Feel free to pass this on to you contacts in ZA.

   Paul Lamar ....In Parkes NSW



Bill Bradburry is having good luck with a dNA muffler. All stainless looks like a
glasspack but has a spiral of stainless angle stock inside.
Fairly  small. He has the stock manifold on the Renesis with a flex joint.

No louder than a Lycoming to my ear. It is in a Lancair Legacy.
Looked at his installation at KZPH two weeks ago.
Lynn E. Hanover


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