From Permalink #90
Did we decide you'd get better scavenging with a radius between the pipes? Instead of V-notching and circularizing the three pipes, maybe cut them with a V-tab and bend it out to for 1/3 of the transition. The cut the collector with three V-tabs and bend them in to close.
Edit: I think there would be less moving metal around, unless you triangularize the collector piece. Or maybe even if...