I have finally cut had the time to cut out the 304 SS (.120 thickness) I purchased some months ago and am now ready for my welding buddy to bring his TIG welder over and tack it up.  The overall length is about 22" on the firewall side pipe, but 21.25" on the "front" pipe, so I plan on cutting the collector about 3/4 inches long on one side to even them up.  Overall the collector will have to shortened up considerably to achieve the more optimum 24 inch length Lynn has talked about for lower RPM / HP applications such as mine.  

 

Maybe Lynn could chime in here and comment on where on the collector that 24 inch point should be located for 5500-6000 rpm operations.  Hopefully where the collector first opens up between the two pipes...

 

If that isn't the case it won't be possible to hit the "optimum" point.  I also am planning on putting a ball joint of some type (type sold by Spruce) at the end of the collector before takes a 90 turn down followed by another 90 degree turn to direct it down the middle of the fuselage to the Spintech muffler I received with the engine.   Anyway, slow progress but at least some progress...

 

Doug Lomheim

RV-9A, OK City, OK

 

P.S.  I didn't have enough hands to really position it all perfectly on angle but hopefully you get the idea...