Al,
I'm biased, running a DMD manifold.
Last year at a so Calif Healey meet I talked for quite a while with an Aussie who knew or had worked for the late David Woodhouse. He evidently had a brief from a rich racer to do as many iterations of their products as was necessary to get the maximum power. This was evidently true of the DMD manifold. Looking at the AHS manifold, I wonder if it has as much effort into it. Looks like a first draft by comparison.
Just my 2 pence.
DMD products are sold by the Healey Factory in Australia.