Hayesey- It's the worst kind of hybrid, made from half genuine half copy bits
The core is genuine which is the important bit. For sure running with no dumpvalve was the cause, just I think the copy gave way long before a genuine one would. The casings on the compressor side are made of some cheap cast ally too, when I was fitting my aquamist the swarf came off in chunks!
Little tip too-I bought a 'K04-15' from e-Bay, just a K03 with a stronger actuator (a proper K04-15 is a machined K03 housing with K04 internals) the giveaway was obvious, and I got a large amount of money back after a few e-mails to the company regarding the VW stamp on the turbo.
Chirs- you should be able to swap the exhaust housings, bit of a pain to do but most turbos will have cracks between the wastegate and turbine.