So, I sold all my really good stuff (Dyns, ARC amps, IDMAX) but decided I was going to do an install in the T4R after all.
this is my Spare-Parts install.
Using:
Factory Head Unit > Navone RHL-2CH line level adapter.
MiniDSP 2x4 will run to the Alpine PDX 4.150, which will then power Focal 165W up front, and a pair of ARC 8s in the back.
(This post for tuning information, later.)