Sound system upgrade 2013 Yaris (South African spec)

[Nelo412]

Hi all,

So, I'm relatively new to the forum so let me first start by introducing myself.
My name is Neloshen (Nelo is fine), I'm from South Africa, (now, for those who think we have lions running around our back yards, yeah the occasional one... just kidding )

So guys, I have been doing a lot of research lately as I am looking at upgrading the standard sound system I'm my car.
I have a 2013 Toyota Yaris (Vitz spec in USA).
I am looking to change the factory head unit to an Alpine CDE-183BT, add additional amplifiers (Digital Designs C5c, still doing my homework for a decent sub amp), a set of splits up front and co's out back, with a 12" or 2X 10".
I want to go the SQ route as I have had my "bass head" days (good memories)...

Trouble is I want everything to function as stock would for example the steering wheel controls, the wiring loom to the head unit (I don't want to cut or splice any stock cabling).

I would highly appreciate any productive input from anyone that has the same model or anyone at all who has anything to share regarding this dilemma of mine.

Thanks in advance and keep it banging
Nelo412