Brian
Excessive oil consumption can certainly be very hard on a cat. converter.
Reminds me when Ford recalled my 1988 Mustang 5.0, to replace the entire exhaust system ( 4 cat. converters ).
In their infinite wisdom, they used " low tension " piston rings ( to reduce friction ), and thus ended up with high oil consumption & contaminated cat. converters.
If you suspect yours is plugged, or partially plugged, you could easily check for exhaust back-pressure with a vacuum gauge.
