2004 4runner Head Unit Upgrade

I'm planning on upgrading my 2004 4runner Limited head unit from stock to a newer Toyota head unit. I bought the T10015 head unit with NAV module (comes out of a 2013 Scion i think) to provide OEM looks but with added Bluetooth capabilities. I have the JBL Synthesis system in the 4runner.

Has anyone done this mod before? I am using "The Ultimate Scion Head Unit" upgrade provided by TheTrackAhead but he doesn't have the JBL Synthesis system in his 4runner. Here's what I've purchased so far:

- T10015 Scion HU
- Metra

$66 TYTO-01 JBL Amplifier Interface Harness, BLACK

TYTO-01 harness (for JBL Synthesis signal processing - although P/N on box says

$69 AXTO-TY1 Digital Amplifier Interface 2001–2015 Lexus/Toyota

AXTO-TY1)
-

$15 Metra 70-8114 Steering Wheel Control Add-On Harness with AUX in Fits Select 2002-2015 Toyota/Scion/Lexus Vehicles

Metra 70-8114 harness (for steering wheel controls)
-

$12 Metra 40-UV43 Male to Female Motorola Antenna Cable, Black (40UV43)

Metra 40-UV43 harness (the antenna adapter) + 1988-05 Antenna Adapter Tip
- Toyota PT546-74120-MC (Microphone kit)
- Toyota PT546-00142 Base Wiring Harness Kit which includes:
~ USB conversion cable (PT546-00120-US)
~ Antenna conversion cable (PT546-00120-AD)
~ 20 to 28 Pin conversion cable (PT546-00120-CH)

I think that's it. Here's some photos of the HU:





Just looking for some tips/tricks or things to look out for when installing all this. I'm hoping the NAV stuff just plugs directly into the back of this new HU as I haven't purchased any adapters for that portion. If NAV doesn't work, its not the end of the world as I 100% of the time use my phone GPS anyways... but it would be nice to have all the OEM functionality just because.