Depends on who your buying it from. Surprisingly there is actually FAKE SSAutochrome parts on eBay, but thats the risk you always take on ebay. Just becareful. I'd rather save up and buy something nice.. like DRAG or Greddy or something.
the manifolds flow well. very well actually, the design they use is quite sound. the quality however is another story. there are plenty of people using the latest gen ssac manifolds and turbos with very good results. there are also a lot of failures. it is a bit of a crapshoot whether you'll get a good unit or a bad one.