Just finished with the Amp install and putting in all the pins in their specific connectors, the AMP is quite the PITA to get in place! My previous post on the mounting position is wrong. Wire Connectors for AMP go at the bottom, two screws are back close to the BCM and facing the passenger side. The two screws do go into the metal plate just to the right and above the emergency brake, half the amp is above the emergency brake, the rest hangs down. I could not get the 3rd screw to go in, there is a hole in the frame tube of the dash for it, but there was just no getting it aligned without having to drill a new hole.
Word of caution for anyone wanting to do this. The instrument panel harness I had was from a 2013 or 2014, and the can bus IHS connector for the Amp was white. However the 2015 requires the connector to be green, there are two rows of canbus connectors under the steering column, one white and one green. Having put the white connector in place, the ABS and several other systems came up "Service me now" warning warning etc, had my heart racing until I figured it out. I checked the 2015 wiring and sure enough it needed to be a green connector. Luckily I had some green connectors, the pins are the same, just had to swap the connector, and all is good. Everything works like a charm. I now have 7.1 sound (with the surround mode turned on, whatever that does) (have to do the two speakers in the headliner some other day to finish it as 9.1)
Big difference over the 6 speaker setup. You can feel the music and the bass thumping in the door panels, and the sub-woofer adds a nice touch too.
On a side note after all was done and working, I swapped in an RA1 radio and gave it a try. It worked and sounded great listening to SXM on it (turns out it has a subscription on it too... not something I've paid for), so yes the AMP work with and will enhance even an RA1 quite nicely.
I did notice the speakers for the roof have smaller magnets than the dash ones. The dash ones are much heavier in comparison and will not fit into the roof speaker mounting brackets.
Turn the volume to 15 or 16 and you can feel the music and not just hear it. I can only imagine what it must sound like to use really good speakers. But I love the sound as it is for now, I can hear the music quite well at 60mph with the windows down which is great.