Has anyone ever seen dyno (or road) tests between a split manifold and a set of "headers", like Fentons? I would be surprised if there would be much difference. Either would help. One advantage (at least to some people) with the split stock (or a Corvette Six) manifold would be the ease of providing heat to the lower surface of the intake manifold. Tom Langdon recommends using engine coolant for intake manifold heat when using Fenton headers.
