Jim, did you clean out the intercooler and pipes, if the original turbo was a total failure there could be lots of oil in the intake and the exhaust.
Is the new turbo knackered, sometimes if the oil isn't cleaned out of the turbo it can cause the engine to really over rev and trash the new one, had the miss fortune of this myself, trying to cut corners, trashed the new one within 15 minutes

If the new turbo is still ok, it could be just residual oil in the exhaust from the old turbo, they sometimes need a good hard drive to burn it off, can take a while, normal driving just doesn't get the exhaust hot enough to burn it off and it won't clear it. It's surprising how much oil goes down the exhaust and how much smoke it makes.