Check out Magnaflow/Carsound's cats. I've bought them from Summit and Hottexhaust before. Good prices.

 

Has anyone ever sold the Cats off their A4? I didn't really think of it but if I have a shop weld in a cheap high flow or something like that I could probably pull down a little bit of recovery cash selling off the old cats for the materials. I know you can get anywhere from like $50-$150 for cats selling them to scrap yards and such, just wonder what the A4's CATs have sold for.

 

The shop that replaced them for me on my 12v put universals in. Total job ran me about $300. When I asked about keeping the old cats he said that he scraps the metal and that's how he gave me a discount. He probably lied. I should've charged him for the ODB sensors he ruined when welding the cats on.

Correct me if I'm wrong but don't we have Oxygen Sensors after the cats?

You may be able to get a set of used cats from Shokan
http://www.shokan.com/used-audi-parts.php

 

All OBD2 systems (and some non-OBD2 systems) have O2 sensors both before and after the cats. The ones after are used to compare with the ones before and see that the cat is doing its job. Don't go for used cats; Magnaflow will be better.

That price is not good.