Well, that's odd, I posted a second post with the part number and it's not on the forum....

The part number for the header with a straight, short (about 1 inch) swagged tube is #KS1564 (this part number is not yet on their website).

A second header, with an exit that points downward (I believe 15 degrees), is #KS1564i. Aircraft International also has a full line of tubes, mufflers, clamps, etc., as does Desert Aircraft.

Hope this helps, everyone! Mystery solved!

I'll post pics of the header on my engine as soon as I get the pieces.

..Rob