This is probably an audio forum question, but I think this forum might provide more answers. It boils down to this; the base system in a 2k2 doesn't use a crossover for its front components, instead just sending a full range signal to both tweeters and woofers. The signal wire running out of the deck simply forks into 2 wires somewhere behind the dash. Where are these forks located on each side? I'm trying to avoid taking a ton of stuff apart to find out myself. I plan to put the crossover for my new infinity kappa 60.5cs speakers somewhere near this junction.
It looks like it would be quite difficult to snake larger speaker wires through the little rubber boot running from the chassis to the door.