First you need an OEM integration piece. Either PAC Amp Pro or Nav TV/Zen (I use the Nav TV).
Then either a DSP and amps, or amp with DSP built in. The speakers in the upper doors are 3.5" drivers and there are tons to choose from. You can make this real easy: Go to see Chris St.Clair at Trixx...
I would NOT recommend anyone buying from Ikon. I just bought 3 pieces from them. The rear bumper/diffuser (some big drip of something on it). The front chin was cracked in 2 spots, and the side skirts were formed incorrect.
You only use the Zen or Pac if you have the B&O. If you don't have the premium audio you can just feed the stock speaker wires (high level) into your DSP. I would suggest a Helix or Arc Audio DSP because they have an input EQ so u can flatten the frequency response.
That isn't included in any package. My dealership found a used one off of an S550 for $60 (mint condition), and installed it in 5 minutes. From Ford parts new they're like $550
The car already has a 190 amp alternator, so that's more than enough. I have the stock AGM battery and a Limitless Lithium stashed away in back. All zero gauge OFC
What amps are you using?