Will a 1.8 T 05 AWP fit into a 99 passat AEB with modifications?

yes... the mounts are the same... just make sure you get the ECU to go with the AWP.... and you also need the fly by wire (DBW(digital throttle control)(or you could use your cable throttle body.) and if you would like more air flow.. use the AEB head.... the ports are bigger... and has more space to move air...