The ones i know:
Fever; apparently runs ok, no problems.
Dave Read: blew gearboxs and gearboxes and gearboxes.....
Raj: ECU lights, bad running, fuel gauge not working properly.
Cho: blew the engine (plus Raj's problems) (and now hes rebuilt is no where near the power TDi claim)
Thats just what i have been told (by the owners themselves).
Recently when a stage two conversion was looked at by another garage (Noble Motorsport) they felt the charger was beyond its capabilities at 0.5 bar and producing too much heat.
kieron (dark is) ran one of the first ones
last i heard it was running ok, and had been for quite a while
i believe maz used to have one as well
Dave Read's blowing gearboxes is surely a testament to the power produced
Or being poorly fitted maybe anything is possible