i might get slated for this but i've read and seen loads of threads and car's with eBay copy turbo's with great success and results, people using them on N/A cars to turbo them, running them at over 300bhp for 2+ years without any problems at all
tbh people wouldn't want to admit that they bought a 'copy' turbo on a forum etc etc only people who mention copy turbo's are the ones that have had a bad experience, in the same sense i've seen people who have had trouble with genuine KKK / Borg Warner / Garret Turbo's
there was a thread somewhere of someone using a ebay turbo on a jap civic i think, and stating how good it was etc etc and then some official garret turbo dealer / seller came on and slated him
Unless someone has concrete proof of how 'bad' these jap copy turbo's are........
K03 / K04 's are cheap nowadays anyway, so personally don't see a valid reason to buy a copy one