If the photo below attaches, it shows the engine being setup a couple of years ago, wedge duct can be seen on radiator, divergent duct is not on the plane but goes under the engine mount, exhaust is all fabricated on farm, manifold is piece of 150x50 mm oval cattle rail 3mm thick with 3 50x25 mm RHS stubs welded to exhaust flange, pipe angles were deliberate to reflect as much sound back into engine as possible, but not restrict flow, seems to work so far. no muffler needed. stainless heat shield now wraps around manifold but not pipe, its this area which is blistering paint so need to stick some foil to inside cowl.
Intake now has small filter attached directly to TB for simplicity.