For readers jumping in late .... all of this discussion relates to the non-Sony 9-speaker system ....
...This just popped in my head, and tell me if it's not even possible...but could you mount the crossovers behind the head unit? (was looking at the pics) Is there enough room?...
Room isn't the issue. At the HU you only have harness for each of the four channels (Front L&R, Rear L&R) ... the harness at that point is not separate for tweeters vs woofers either front or rear
. So, while you might fit the xo's there, you will then have to pull wire from that point to each of the separately xo'd speakers. I can't see any advantage in that.
... Or even run a loop straight down toward the floor, mount the crossovers there and connect that loop back up the head unit wiring? Then you could keep factory wiring running to the A pillar and doors, right? I'm just doing a simple speaker upgrade, mostly use this vehicle for work. (Kicker 40CSS654 a possibility)
It is very hard to grab any of the speaker wires at any of the pillars (A- or B-).
Recap of harness routes:
HU > split buried deep behind dash
Split out to tweeter > stays buried in dash to tweeter on each side
Split out to woofer > to lower console C214 > Under front seats > along base of door opening to A-pillar each side
HU > to lower console C214 > Under front seats to B-pillar each side
Split at woofer connector in the door > up to tweeter in the door
In all cases, the OEM harness is carrying a full-spectrum audio signal all the way to the connector on each speaker frame (harness wiring to ALL woofers and ALL tweeters); nothing is filtered except by the capacitors mounted on each speaker.
With the Kicker 40CSS654 having a single-box xo for each side with both HP and LP outputs to woofer and tweeter, I can see two choices for the front if I were going to try it:
1. Mount the xo's in the lower console area (there's plenty of stash spaces); find the wires out of C214 for the front woofers between C214 and where they dive under the seats; cut those wires, use the C214-side for xo input; use the underseat side for the xo woofer output; run new wires from the xo tweeter output > under seat > under door trim > up to tweeters (insulate and abandon the OEM tweeter wire ends, they'll still be 'hot'). This avoids the dread post 23 procedure.
2. Mount the xo in the door as suggested in the Kicker installation manual and run a new wire out of there up to the tweeter (the dread Post 23 procedure).
Having been all over this car's audio wiring, I'd go with 1 (actually, I'd not use that type of xo for a speaker-only replacement).
For the rear, mount the xo's in the doors exactly as shown in the Kicker installation manual, using the OEM wire feeding the woofer as the xo input.
IMHO any speaker using a single xo box to feed both woofer and tweeter like the Kicker model you cite does not
meet your criteria for "...just doing a simple speaker upgrade" for the Escape front. They may well be nice speakers but the installation is inherently not simple. Not worth it, IMHO, if you don't intend to go farther into separate speaker active xo's and/or DSP (and then I'd go with different speakers anyway). There's too many other choices in the price and quality range of those Kickers with easier to use inline passive xo's for this installation. You can use the treble setting on the HU to adjust EQ of the tweeters relative to the woofers.
From post 23 you can see I've gone to the great trouble to essentially re-wire the FE downstream of the HU. That only because I've gone totally nuts
and am now running a DSP, 9 discrete amp channels and 3-way active xo speakers in front. Yeah, it sounds great but the install does not pass the "simple" test by a long shot. Short of that degree of audio madness, I'd do all I could to avoid the post 23 procedure.
As always, my opinion is worth exactly what you're paying for it