I purchased a Euro BEX ECU PN suffix AS, and had the immo turned off. The ECU works good in the manual transmission A4, US spec, 2003 models, but without the different injectors, the fuel trim eventually reaches the max adaptation limit. The turbo used on the BEX 190 hp engine are slightly different from the US AMB turbo as well as the BEX DSMICs. The exhaust manifold is a higher flow version of the AMB part too.
I originally wanted to run the BEX-AS ECU on my AMB tiptronic, but the ECU won't accept the soft coding value required for the tip trans with the AMB 1.8T. I loaned the ECU to a friend with an '03 A4 MT, and it ran well with the exception of the lean fuel trim limitation that occurred. His setup has a test pipe and a hot air intake also, that may effect the fuel trims.

I'm sure the EEPROM contents would be usefull - I am trying to get a Canadian S4 cluster (not sure about the IMMO version) to talk to a US S4 T-box and would appreciate this info - sure I would need it at some stage...?