Just a quick question really - is this possible? I have been on the Kufatec website and spotted this; KUFATEC GmbH & Co. KG - RNS-E Bundle RNS-E Adapter + antenna adapter + Unlock key 34521 Would that do the job? - The car currently has a Symphony II (non bose). If I upgraded to the RNS E - would the standard rear subwoofer still work? Many thanks!