GUYS!!!
youre using a litre per 100 miles roughtly!!
if you still have the cat on the car, and the turbo seals are pumping oil into the exhaust, then the EGT will raise considerably and the Cat honeycomb will catch the oil and burn it off so fast that youll see hardly a drop of smoke out the back!
if the rings were gummed, or lined up wrong, youd have NO compression to talk about, and youd use MUCH more than you are!
Pull the plugs, ill bet theres hardly any residue there at all!
Pull the intercooler inpipe, and you should see minimal oil. Im laying money that the intake side isnt whats using the oil. Ill also bet that the oil isnt getting past rings in that way, so id be inclined to pull the downpipe off, and have a look round the wastegate and the exhaust impeller! ill bet youll find the culprit in the turbo!
If those seals go completely, then even with a cat youll get smoke out the back. But the amount youre using is probably burning off in the cat itself. And the oil consumption probably only happens when the engine is hot, and the Impeller shaft seals start to leak.
If you had no cats at all, id guarantee you would see smoke!!!