Well, after a lot of googling, I got some conclusions:
First I'm gonna do is to replace the turbo vnt ring.
When I changed the turbo core I kept the old ring, because it moved okay and I thought that still could be good.
But it seems that it wasn't well enough, due the low boost before 2500rpm, it's acting like a classic turbo.
I saw some graphs and they should give 0.9-1bar near 2000rpm, while mine was giving a &/$%, luckly 0.4-0.5 bar.
So I ordered it from Germany, it's 93 euro including shipping to Spain.
Next will be disassemblying the turbo and polishing the exhaust housing, so all the oxide and dirt goes and the new ring will be happy to give me the boost I want (damn, I want my bloody alfa back
Correct me if I said something stupid and should be trashed to death...
About the noisy whine, I dropped some lithium grease in what I think is aux idler, and the noise went barely audible, so I got the guilty part.
Still some noise there, could be the chain of the oil pump, or all the other pulleys in the engine.
But its a diesel, driver it by 2500rpm and the noise is covered by the tank noise
This is the part, not my pic, got from the web: