Hey everyone,
I successfully did a full radio upgrade in my 2007 MZG, it was hard to find any info on how to, so i hope this helps someone in the future.
overall it was fairly easy. I used the beatsonic harnessess for the entire install.
I used the SLX-131 from car audio express in the UK, if you get the steeringwheel package it already comes all wired up and ready to use, they also include the radio side adaptor which you configure yourself with the guide included, you do not need to buy any extra radio side hardness. This kit also came with the dash kits and everything needed. Beat-Sonic SLX-131 Audio Adapter for Toyota Alphard (caraudioexpress.co.uk)
Wiring of the SLX-131 was very easy, its all plug and play, just get the right plug connectors, and everything plugs in. You only use the front L & R speakers from the radio side harness. You dont need to hook up the Ant Rem either unless you have a remote antenna.
For the front and rear cameras you will need BC1 and BC15. These two kits install under the passenger seat, there is an ECU there with a 40 pin connector. You will need to run ACC+ and two RCA lines to under the seat. I was lucky enough that the car had previously had the TV module installed under the passenger seat so I had ACC power already available. You will hook up the BC1 in the front camera configuration, with the purple going to red. I ran the two RCA cables just under the floor mat to under the glove box and then up through the dash to the new radio headunit.
Beat-Sonic BC1 Rear Back Up Camera OEM Interface Adapter (caraudioexpress.co.uk)
Beat-Sonic BC15 Reverse Camera Adapter for Toyota (caraudioexpress.co.uk)
I used the Pioneer DMH1500NEX headunit for the replacement radio, overall it works fairly well, but doesn't have wireless carplay, and they use their own OS which is fairly limited for videos. It is Web Link compliant, so I can watch YouTube and app store videos on the rear and front displays.
The rear display also is working, but with this head unit is fairly limited on what i can play. I would definitely recommend getting something with an android OS for more video flexibility if thats what you want.
You may also want to consider a unit with HDMI input as well if you want to have more video input options.
I will upload a video on to YouTube at some point as well.