Ok, I have the answer now. Apparently, the BRD was the only engine that came in the B7 with quattro. This means proprietary ECU and injectors. So, in order to make the ECU and ABS module compatible, I will need a BRD ECU, wiring harness, injectors, and possibly a few sensors. As mentioned previously, the BRD uses a Siemens ECU, not Bosch and the injectors are piezo. I doubt this will help anyone in the future, but you never know. Nothing like reading through endless forum posts just to find the typical "thanks everyone, I figured it out" with no other details. So frustrating! Thanks again for the help.