Opel Zafira B OPC Z20 LEH Turbo disassembly
To remove the core I eventually gave it a firm tap on the compressor wheel nut, after applying WD40 to the joint in the manifold.
Then the core just drops out of the manifold.
I want to make the compressor housing nice and shiny, because I can.
I think I destroyed the core (was going to be replaced anyway) by trying to undo the compressor wheel nut, thinking that this was stopping me getting it out of the manifold. But it's just a press fit into the manifold.