I missed that pic Dan, maybe just a couple of short bends trimmed down to merge into that main junction where it feeds the turbo, but a baffle running down the centre of the 2 & 3 runners would serve okay (frankthedolphintrainer's manifolds had this)I thought you had mentioned the baffle a while back.

I suggest runners 1 and 4 came into the collection on top and underneath of 2 & 3, that includes a few more bends though and would affect costs.

Well spotted but I wouldn't be too pedantic about it seeing that the valve will be closed anyway, and the passage to the turbo open good time to mention it though.