No, the risers are not wrapped as the never get that hot. There is a lump of carbon just inside the edge of the turbo housing where it faces up to the riser that will have to be removed judiciously, as it is close to the turbine. What I found interesting, was that the riser fit is metal to metal on to the turbo housing, with no gasket. I called my merchant marine chief engineer son about it, and he said it was common practice even on large ship diesels to have metal to metal connections.