You need a new cat when your vehicle's emmissions reach unacceptable levels. New cat at 106,000km? Seems pretty early for a new one. I don't know how it is in Canada but I know here in the US we have a federally mandated 8 year 80,000 miles (don't quote me on the exact numbers, but it it something like like) emmissions warranty on cars.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record