FR&R Tuning used to advertise a hybrid upgrade for the K04. Its not on their site anymore though.
£595+VAT - includes a K24 compressor wheel. clipped turbine wheel and an upgraded bearing.
Universal Turbo's offer an upgrade also
£500+VAT - includes a bigger compressor wheel (type unknown), and upgraded bearing.
They dont clip the turbine wheel but can do free of charge if required
Both of the above include a full overhaul.
If the turbine wheel needs replacing this works out at approx £150+VAT