I'm the guy with the stock 987 headers. They are supposed to be from a 2006 Boxster S. Since that is a 3.2L car, I'm not sure that these have the larger port openings that are needed for use with a 3.6L engine. The primaries are clearly larger in diameter than my stock 2000 3.2L headers, and the design is better overall than those headers.
My preliminary research indicates that the 3.4 Cayman S and 2007+ 3.4L Boxster S were built with the 3.6L cylinder heads. If that is true, then stock headers from a 3.4L Cayman S or Boxster S would be a good fit on a 3.6L swapped 986. Perhaps Porsche used the same headers on the 2006 3.2L Boxster S
and the 2006 3.4L Cayman S? I am unable to prove which model years these headers are supposed to fit because the parts catalogs are not working (I get a 404 not found error) on Porsche's website. If I had a header gasket for a 3.2L or a 3.6L, I could figure this out pretty quickly. I do know that the port measurement at the flange is 1 9/16" x 2 3/8"
Here are some pics:
For comparison, here is a pic that "tholyoak" has previously posted. Top is a 3.6L gasket and bottom is a 3.2/3.4L gasket.