There has been quite a bit of talk here lately about oxygen sensors; how about a comparison to a related item- catalytic converters?

I'm buying the GoWesty stainless exhaust while it's on sale. Since I'm installing it on my 1.9, I need to get a 2.1 cat with the oxygen sensor hole. Since I'm in CT, I don't need a CA CARB compliant cat, so I can go with the 49-state cheaper cats. 

From what I've found, most come with a 25,000 warranty on the performance, and a 5-year, 50,000 mile warranty on the body. I've seen a few exceptions, though- Advance only warranties their Magnafows for 90 days, though they say that the longer warranty applies through the manufacturer. Autozone warrants their Bosal for life.

I've seen some size difference specs, though I'm assuming that a small difference won't affect installation. I've seen some listed as 11" in length, and some 12". 

Prices range from $89 shipped from RockAuto for an Eastern, to $137 (but $87 with coupon code). So I can get one for under $90.

Has anyone noticed differences in fit or quality among the brands? Some are round and some are oval; some have heat shields and some do not. 

The major brands seem to be Magnaflow, Bosal, Walker, and Eastern.

Feedback is appreciated. 

Thanks,
Ed in CT