Someone knowledgeable about s400s?

Looks like smaller than a 75(71) also you can buy it new for $650ish
 
What website would you recommend if I were buying new? And my last question is the 1.1 housing worth the extra change?
 
Just look around for them, also the turbo they have pictured had the larger turbine. A 1.1 on the larger wheel is a custom turbine.
 
That turbo has a 71mm compressor, and they can be had for less than $700 new.
 
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