Looking to buy a 2009 Alphard but I want to be about to install a English head unit and have all the OEM features. The 2009 I'm looking at has the 270 camera and 4 speakers in the headliner. Which Oem stereo system is it equipped with? Amplified? From the pictures I seen of the interior there are only 4 speakers in the headliner maybe a 5th. Will it be simple headunit swap or will I need a canbus box and wiring diagrams and splicing of wires to get a head unit to work?