that's probably my fault because I said Turbosaver.
The ceramic impeller was very light and very fragile/brittle. The mig wire problem might have been the primary fear. We know that even the steel blades have been nicked by something that went thru them. Many cases it was a piece of head gasket, ground electrode from a plug, etc., but there may have been a legit fear of a piece of wire as the welding was pretty crude on the factory headers on the inside. Or maybe weld slag?
We used to weld them on the outside and then port them a bit to smooth them out and take rough areas out of the airstream