I'm a grad student in mechanical engineering and I've spent a lot of time looking at flow visualizations in water and wind tunnels, so I'll give you my thoughts. I have no experience designing intake manifolds, though, so take anything I say with a grain of salt. It seems to me the two biggest problems are the protruding velocity stacks and the abrupt expansion right after the inlet. Pipe flow will tend to separate and go turbulent when there is a large area expansion, like there is at your inlet. Also, the protruding velocity stacks are bound to cause separation and turbulence. I don't know if it is common in this type of EFI intake, but I would think it would be a lot better to have the face of the velocity stacks flush with the surface of the intake manifold rather than protruding into it.