im going to agree with you on this ninja... most of this stuff is all the same. there are somethings that i would buy from a known name brand, but this is one thing that i thought looked identical to the cusco one.. so i bought it.
Check out tube diameters, bends, and the weld areas.
What I mean is most of the ebay parts are all the same. They have gotten much better over the years though - the bearing on the Wicked arm actually seems to be a vehicle specific bearing unlike the older one's that had thin walled housings and grease fittings. Teflon coating ftw. I think that arm looks pretty solid.