If you want some really significant improvement, why don't you just go with true active bi-amping or tri-amping and eliminate the passive crossover network entirely? Doing this also makes the cables that connect to the drivers much less of an influence.

Futzing with speaker cables, especially when there is a huge liability with the speaker's passive crossover network, is really barking up the wrong tree.

Active crossovers are a massive improvement compared to anything you can do with the passive crossover still in the speaker cabinet.