Catalytic converters

[danzigfan]

Hi guys, I'm going to pull off the heads, replace gaskets and replace cambelt etc...while allready being there, I'd like to replace cats. Reason being Omega passes barely passes mot when exhaust gasses are measured. It's worse every year. Local parts shop doesn't find any cats for 3.0.  I've found some on ebay for 2.5 and I need to know if they would fit.
And to add, would new ebay cats for 250€ do better than the ones on the car? The price seems a bit low..
Thanks in advance, Stan

[TheBoy]

In our experiences, which are mostly UK based, the 2.5/3.0 cats are brilliant, and last well.  Generally it's the rust that kills them, rather than the insides.

The 2.6/3.2 are generally crap in comparison to the earlier ones, much like most of the engine, but still better than the aftermarket ones.

The emissions you are getting close to failing on, are they ones the cats will solve, or do you have another underlying issue?