I'm running a Kenwood 5140 in-dash, Nav unit with bluetooth. I love it, and everyone thinks it's factory. You can adjust the illumination to match the factory green or change it to match the "my color" gauges. Shallow mount subs from Kicker or Pioneer (IMPP) are nice and work well to replace the door subs on the shaker systems. These have to be a shallow mount, as there are depth constraints. As in all late model mustangs, 6"x8"s round out the rear deck and door mid/highs. There are brackets available to place 5-1/4" speakers in the doors and deck, if desired. You can check Crutchfield.com for fitment and specifications and then place an order or shop the items for best pricing. I shopped local, because that's how I roll.