I switched over from an E90 to an A5, must say it’s a great car. Was disappointed there was BT for calls but not for music, so I installed a Carplay interface. Takes around half an hour if even. Well worth it, and uses the OEM radio
I have a 2009 A5 sline special edition, and I had the Hnav software so I went with that box. and I got the carputech brand, I got it straight off their website as they had an end of year sale and got $50 off with their code"NEWYEAR".