Because it was rebuilt many times, because it was like all other hybrid turbos, just another hybrid cobbled together with bits out of bigger turbos.
It's just a waste of money, I don't know a single person who has fitted a hybrid and been "happy" with it and not upgraded it within a couple of years. I think you'll follow suit eventually.
Besides, most K03 hybrids struggle to see more than 270BHP. Fair enough K300's have gone up to K04 numbers. But my logic is...
A K300 is £700 for the unit alone. A K04-064 could be fitted for another £3/400.
A complete K04 setup is £350/400.
And add the additional torque and low spool up of the K03 hybrid you'll be wanting rods too if you want to be able to sleep at night.