CEL is on and took it into the dealership and they said it needs a driver side pre cat and quoted me $1200. Has anyone experienced this issue? Is there a cheaper alternative? DEC makes catalytic converters for audi's for about $400 but i'm not sure if it also comes with a pre-cat or just the main cat that goes under the car. I also think there are more than 1 pre-cat. Any help is highly appreciated. Thanks.

See if you can't get the part no from the audi dealer, but you can get the drivers side cat here http://www.catalyticonverters.com/shop/?N=9190&Nr=OR(AND(make:Audi,model:A8%20Quattro,yea r:2001),AND(universal:1))&Vi=9612+4294967264+1574& y=2001&mk=Audi&md=A8%20Quattro
much cheaper.

Looking at parts list for Audi A8 97-03 shows no such thing as a Pre-cat. It shows only a left or right side unit. The Right side appears to be integral with the Right front exhaust pipe and the left side is free standing.
Part numbers are Rt.side-4DO 254 550 BX
Lft side-4DO 254 400 BX
AlbeeG

Does that mean if I buy a catalytic converter, it should come with header pipe that comes down from the block...which supposedly has the pre-cat?

Were they maybe talking about the pre cat 02 sensor? I'm not familiar with a par on these cars like that which you are talking about. Do you konw what the CEL error code is, or what part number of the part that the dealer was telling you needed to be replaced'? If not try and get at least one of those peices of info.

The Catalyitic converter on the right side comes attached to the exhaust pipe. The left side converter appears to bolt on to the left exhaust pipe. In other words the right CAT and exhaust pipe are ONE piece wheras the left CAT is seperate from the left exhaust pipe. I am again looking at an actual audi parts list and there is no mention of a Pre-Cat. You really should clear this up with the dealer. Perhaps someone like AudiTech may know the right answer,
AlbeeG