apparently the main difference in the non-universal O2 sensors is the wiring length and harness plug.

THE AUDI NEEDS THE CORRECT O2 SENSOR (FACTORY)
YOU WILL THROW ALL KINDS OF O2 HEATER CIRCUIT FAULTS AND NOT TO MENTION SENSETIVITY ISSUES.
THE AUDI BEGS YOU NOT TO CHOP OFF AN EAR AND PUT ON A TIN CAN INSTEAD.

It doesn't even come with a connector.

It's still a Bosch. I'm going to throw it in and report back to y'all.

Bought 4 of the 25 buck VW sensors, chopped ends. soldered old ends, works perfect. No codes.

Hey, I really hope it does work for you. It's just that I have seen quite a few problems with o2 heater circuit faults and internal resistance faults too large with universal o2 sensors.
Mabey that's not an issue now. Good luck with your repair and I hope it goes great.
MORE POWER TO THE AUDI

It was simply a matter of cutting the connector off the old Audi O2 sensor and splicing it onto the new Bosch universal. The wire color codes are the same (black to black, silver to silver, white to white x 2)

Here's the post I logged on the A6 C5 forum about a month ago. The VW sensors work just fine:
'I did my 2.7T a few months back -- both front (pre-cat) sensors (I used VW sensors fitted with Audi connectors). Here's a quote from an earlier post: "In place of the Audi O2 sensor, get a couple of VW sensors, part # 06a 906 262q for about US $25 each and then Audi plugs, part # 3a0 973 334 for about US 80 cents each. Break the plugs from the VW sensors down to metal connectors and blue seals [this can be done easily in a vice by closing the jaws on the VW connector lengthwise -- no harm to the electrical connections/wires] and connect the ends to the Audi plugs and install. The wires on both VW and Audi sensors are numbered on the plugs -- mark each wire and connect to the appropriate number." I've got both a socket and a crow's foot O2 sensor wrench, but the crow's foot worked better for me -- it _is_ possible to get it into a narrow slot on the driver's side (to the left as you're facing the sensor), but there's a relatively narrow angle of turning room, so you have to lift the wrench off and reposition part way through each turn. The passenger side sensor is more accessible. The crow's foot doesn't require clipping or severely bending the electrical leads, unless somehow you have a particularly deep socket. I used about four feet of extension and -- very important -- a wobble extension for connecting to the crow's foot. It may be possible without one, but you can save yourself a lot of grief finding the right position with a wobble. The series of extensions came out over the fender, from which it was fairly easy to apply the requisite force. Undoing the originals turned out to be like unscrewing a spark plug -- a fair amount of resistance, but once they give, they're loose. Somehow, I was expecting them to be more stubborn. In fact, the sensors are fitted with similar compression gaskets. To apply torque I used a 1/2 inch breaker bar in combination with a 1/2 to 3/8 converter. I've got a bunch of pics of this escapade and have been meaning to do a write-up for a while, but just haven't found the time. Best of luck.'

do you have any pics?
I am about to change my Pre-Cat 02 sensors and i an having a hard time locating the drivers side sensor.
Should i change the 02 sensors on the Cat?