As to pulling better wire. I just looked. Yes it is possible, as the 4 binding post mounting plate near the bottom has 6 screws (on the 3.4s it is a concentric driver, meaning 2 sets of wire). As to pulling new wire, it would need to be thin-ish to get both through the hole. That said, the wire from the speaker to the binding post is much thicker than the crap wire provided to jump to the XO. One could also simply run new thicker wire outside the back plate
hth
hth