I had the same problem with my oil pressure, I took the oil feed adaptor out, and tapped it M8 as the bore was 6.5mm. I then made some little restrictors from M8 grub screws, drilled through them with different size drills starting at 2mm upto 4mm.
I fitted the 2mm restrictor and it did the trick, the turbo stopped smoking but the oil pressure went even higher... The excess oil pressure eventually (after about 15 mins) forced the oil pressure release valve in the oil pump open and everything returned to normal, been good as gold since!
Heres my thread.