I made the following at home audio install in my 2019 Ecosport S over the course of last year making the best utilization of my COVID work from home gig with my dear enthusiastic dad. I am an audiophile pampered with Klipsch Reference Premieres speakers, SVS subwoofer for my Atmos HT setup, Boss QC 3.0/Sony WH-1000XM3 for headphones. Although stock 7-speaker Sync 3 system sounded better than lower variants, being picky about my sound and I was not very happy with the clarity, bass, resolution and high distortion at high values with stock audio. Having experienced what a DSP does to improve music to your taste on my HT setup, I got to work quickly and installed the following things in that order:
1. Puzu PZ-C31 DSP bought from Aliexpress (31-band parametric EQ, 4-IN/6-Out, 4-Out with amplifier with 20W at 0.1% THD, Max power 48W @ 4 ohm load per channel based on the Class AB IC TDA7851) - Installed through a T-harness in to stock Audio Control Module (ACM). So thankfully did have to cut any wires. Got it in 2019 well before the ban.
2. Focal acoustic insulation kit inside doors, tailgate, few areas of the floor.
3. Focal PS165V1 component speakers in 4 doors (running on the DSP amp in the interim)
4. Hertz Dieci 87.3 coaxial center speaker running on stock audio (some say center is not great in car audio, but I like it for better sound staging)
After the install, I liked the bass response and clarity. I time aligned and then calibrated the system against pink noise with a Dayton mic I use for my home audio. Ford also processes stock audio to match cabin acoustic profile, so used Forscan software to config ACM, enabled Flat EQ output and full-signal to all channels (by default it sends full frequency range only to front and low frequencies with high frequencies cut-off to rear. In case you installed components at rear then tweeters are deprived of their potential). Also at high volumes around 16 or up, stock audio will start cutting off low range frequencies to protect stock speakers. I hear this is common is most cars. So match gains and tune system accordingly so that you will not exceed this volume.
Being a EHS professional, I had calibrated Noise monitoring equipment which confirmed my readings. Center was borderline absent/inaudible as stock system was not pushing enough juice for the Hertz and at high volumes I feared the stock audio and DSP were pushing more distortion. Tweaked gain and tried my best to keep distortion lowest. I was happy but I was sorely missing the kick in the chest as much as I was missing my girlfriend.
5. Took out the Alpine MRP-F600 4-channel amplifier from dear old Verna and interfaced with the DSP. Now my components run clean and to their full potential on Alpine amp. Hurray !!!
6. Got a 12" Rockford Fosgate T1D2 subwoofer and had a speaker guy build a sealed box as per my calculations. Placed it in the boot and ran it on a JBL Club A1KW monoblock (Replaced with a locally made Interfire later as it went kaput). Low range signal was provided by the DSP.
7. Was not happy with Center speaker being useless or used less on stock system.
Puzu DSP doesn't offer audio channel mixing/summing (this did not affect sound performance but it's like an itch that won't go away). Got a Dayton DSP-408 and replaced the Puzu DSP. Sound seemed little clearer (confirmation bias, hmm?) and I didn't do audio summing, not surprising

.
Pros: Interface looked polished, audio summing, remote display Cons: 10-band EQ per channel, external BT adapter
I had an extra Hertz speaker lying around (Package contained a pair for the center). It was time to let imagination run wild. Drilled a hole in rear parcel tray, placed the second center at rear. Wired the Puzu DSP now to both front and rear centers. And then I rode into the sunset happy. One small mod done by a man is a huge step for more mods. I have more non-audio mods on the line once I get back. Will keep you posted.
Being an audiophile, I have been following up this thread like a stalker from before I even got my car. It has been very informative and motivated me to do all that I did. I would like to thank all other fellow enthusiasts. I will make a more detailed ICE upgrade post or update this with pictures (I only got a few currently) at a later time as I am away.
FAQ:
1. It is a clean install. No wire cuts anywhere. I used T-harnesses, wiretaps, fuse taps, Scosche connectors etc. wherever I could. Only permanent damage I did was cuts I made to A-pillar, rear doors to install tweeters and rear parcel tray to install center.
2. Amps and DSPs were placed under the rear bootfloor tray over a MDF board. Ecosport S variant gets a height adjustable tray I placed it on first level and there was ample space down under.
3. Stock speaker cabling was retained as Ford cars have connectors with plugs between door and body. Pushing of wires through a rubber grommet is not applicable. Power runs through the battery using a 4 gauge copper wiring and connected to DSPs and amps from a distribution block.
4. Except Alpine amp from old Verna, and Puzu DSP from aliexpress, rest I carried from Germany.