I've purchased crap from ebay and popular Z vendors too. Basically it's "Caveat Emptor" or "let the buyer beware" I would never buy cheap copies of technical items. In the long run it will end up costing more. One exampe of where it pays to buy cheap copies is Z test pipes. The Chinese copy is just a good as the name brand item. It's doesn't require much technical expertise to make them and over charging for them based on one's name is wrong in my book.
I did buy a set of cheap Godspeed inter-coolers on eBay and was pleasantly surprised by the excellent build quality and fitment. I did have some grinding to do on the mounting tabs but all-in-all they are a great deal. My basic bench testing indicates they are as good as the Greddy. I have one Greddy SMIC left over from my totaled Z to use for comparison. I dont think the Godspeed Intercoolers are knockoffs so I felt justified in buying them. To me they look like an original design. They are bar and plate, most Z intercoolers are tube and fin.
