I had a fascinating conversation about this with Adam Christian (LinkedIn) at the 5.2L engine reveal with SID297 a few years ago. He led the Voodoo engine development team. He's pretty handy too, having brought home some tubing to fabricate a set of shorty headers for the Coyote program when nobody else could do it right. Tubular exhaust manifolds were nearly abandoned in favor of cast iron and Adam pulled this one off at the last minute.
For a better understanding of the matter at hand, take some time to read through the patent he and two others at Ford received in 2013.
Patent Images
For a better understanding of the matter at hand, take some time to read through the patent he and two others at Ford received in 2013.
Patent Images