Hello Volvo community! After giving me some good tips on the purchase decision, I now have one more question: In the V50 is the Audopaker High Performance as well as a NAVI RTI with DVD drive. Can I expand the radio and install my own? Just in the summer I bought one with USB and Bloototh freephone device. I would like to use this further. I would like to thank you in advance for your help.