So......I own a 2004 with the Bose system.
I replaced the dash speakers with these:
https://www.ebay.com/itm/PAIR-JBL-GTO428-4-inch-2-ohm-105-watts-Car-Audio-Speakers-repl-GTO429-/281288625734?hash=item417e1bce46
Only required some minor cutting with a Dremel tool.
Easy, peasy.
What surprised me, was that they not only improved the sound quality, but the entire system volume want up by a pretty significant amount of db's.
If you can find any of these left somewhere, I highly recommend them as a simple plug-n-play mod for the Bose system.
The head unit and everything else is bone stock in my car.
I like where you are going with the crossover, but like the other folks said, these drivers are sub par and getting old, so you should really upgrade the whole speaker system.
FWIW, from my experience above, just R&R'ing the dash speakers alone makes a HUGE difference with the Bose system. i'm getting WAY more base outta the sub woofer and the door woofers just by changing the dash speakers and nothing else.
Good luck, keep us posted.