I have a focus Ti also and I'm going to replace the stock speakers with better stuff and run an audiocontrol LC7i an LC6i and an EQS along with my own amps and better sub. I'm waiting on my tax return to fund the project.
In the mean time, pop the cover on the center of the dash and unplug the center speaker, it will improve the soundstage.
There are 6.5" mids in all 4 doors and tweeters also and an 8" sub in the trunk or hatch. Look under the spare tire cover in the upper left corner you will find the factory sony amp. It has 3 plugs on it, the top one has the sub out put, the center plug has all 4 mids and all 4 tweeters on it. you will have to trace the wires to find out which is which, but that is where you want to tie in your LOC. Since you will be using an amplified signal, you will need a good LOC such as audiocontrol stuff that can handle up to 400w input, not some cheap 10 dollar piece of crap from pep boys or vato zone.
Since there are separate signals for the mids and tweets coming from the amp, an LC6i, or 7i or 8i can sum the input signals back together so you can run one channel per door and run your own components or coaxials or whatever.
If you do it right, then everything you have now will still work, it will just sound better.
13 Blue Flame F150 FX4 402A on 20's loaded
13 Frosted Glass Escape Ti 401A loaded
13 Performance Blue SE 201A
14 Dark Side Fusion SE 200A
L-CCC #18/HOIA #37