I want to install a full radio system. Subs,New Speakers,Etc etc. I do wanna retain my back up camera and steering wheel controls. I actually need those due to my horrible eyesight.

 

You add something like the Audio Control LC6i. This uses your existing stereo ( retaining all its functions & accessories)

The LC6i then allows the running of amplifiers & speakers, along with a dedicated sub output.

https://www.audiocontrol.com/car-aud...-upgrade/lc6i/

I'm running the LC6i in my 2012 Mazda 3. I still have the factory stereo with its GPS & bluetooth, but running a decent sound system.

One look at my car & it still looks like its the factory system.