Looks like a really nice design. The cooling exits look a bit like Peter Garrison's Melmoth; I think he had good luck with the design. The 'turbine' exhaust exit does look cool. :-) Did you include a muffler, or did you just turn the stock exhaust manifold exit out the side? How are you protecting the cowl from melting near the pipe? Looking forward to seeing engine installation pics. Keep 'em coming (or just put them on a photo sharing site).