The best performing manifolds for import guys has always been the HKS or some of the Greddy stuff, they made their manifolds a different way(stake formed or cast) to minimize hotside runner length. Other people for the same motors used preformed fittings, and their manifold volumes and size were dictated by how their materials went together rather than what the turbo system really wanted.
The success of the HKS, Greddy, blitz etc turbos on imports was also because they did tons of R&D on Turbine/compressor balance to see what works best for the 2-3 litre class motors, their target market. Even though there are more efficient wheels out there now, nobody just off the shelf picking of the newer turbos is surpassing what was done with the now old HKS designs, which were Garrett centers sections altered and trimmed to fit HKS turbines and compressor housings.
Be nice if a big North American company would do the same for V8 applications, take a lot of the guess work away. A lot of people do get good results by buying a few hot sides and getting close, but how optimized are these setups? I don't think there is anything out there like a specifically trimmed turbo for 5-6 litre motors @ xxx rwhp etc.
On a sb or BB dodge the best option might be OEM style manifolds, rather than inverted long tubes. I can't remember if the BB manifolds are symetrical so they could just be turned upside down.




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