[GuidoK]

No I'm not being a donkey for the sake of an agrument.
You have no idea if that ebay manifold will expand with boost (expand isnt bad but crack is), and you have no idea what the flow is to the itb's. The boost on that ebay kit is low anyway.
As long as it doesnt cracks, its apparantly strong enough. Do you see cracks?

You depict properties on that thing on the basis of how it looks and that it's not neatly made (tbh I'd like to see you do a better job, are you familiar with aluminium tig welding? I am.) and is of a different shape than the ones you're used to, but that's an opinion not based on knowledge or research.
And then I'm being a donkey?
You think it has to be wedged shape, and I post a picture of an F1 car with a boxy shaped turbo inlet manifold. I think those guys thought it through too dont you think?
If its a different shape, it doesnt automatically HAVE to be wrong.

You dont even react to me discussing one of the most important aspects and that is the plenum ratio or the function of the plenum in general. Why is that? If you want to talk performance on turbo manifolds that's surely something to be discussed....
I can think of several points where that ebay intake can be improved upon (like maybe the relative small inlet piping diameter or that it takes a tight corner before entering) but the fact that it looks like a lepers face doesnt have to restrict performance imho.
Also the sharp edges you talk about are just as sharp in your examples if you look at the air path from plenum to cylinder. how the intake runners exit the manifold are 90deg corners, in both examples. How the air enters the plenum is of less importance than how it exits, because the air going into the cylinders isnt phased with the air going into the plenum. Thats the function of a plenum, a buffer (and its the size of that buffer that matters, and that might be on the small size in your first example as I wrote before, it sure is smaller than that ebay intake). On a NA intake thats completely different, that uses a resonated air ram effect when properly designed (helmholz resonater/spring mass system).