Oil Pressure And Misfire

[nissyline]

Hi all fairly new to SAU, just got a few questions if anyone could help??? recently bought my 2nd R33 for 7K, it used to be a non turbo auto, but is now turbo manual... not sure weather the turbo just got slapped onto the N/A motor or if it's had a new engine, it's done 157,000kms and i've replaced plugs, oil, added a cooler and lowered the boost from 9psi on a bleed valve back to the standard 5-7psi solenoid... my main question is after a the car is fairly warm about an hour of driving it nearly has no oil pressure and when i get into it, it has a really bad misfire like it's detonating... any ideas or feedback would be much appreciated???