The project is ill-advised.
To at least match the performance you have now will require duplicating the transfer functions at the driver terminals (duplicating compensations for rising response, baffle step, driver resonances, etc). If you're willing to invest that much time you're better off building better speakers designed by someone else.
To beat it you'll need to learn what you're shooting for, make gated measurements of the speaker's polar response, and come up with more ideal cross-over functions. At this point you've decided to make speaker design a hobby and with all the time going into the effort you're better off starting from scratch.
To at least match the performance you have now will require duplicating the transfer functions at the driver terminals (duplicating compensations for rising response, baffle step, driver resonances, etc). If you're willing to invest that much time you're better off building better speakers designed by someone else.
To beat it you'll need to learn what you're shooting for, make gated measurements of the speaker's polar response, and come up with more ideal cross-over functions. At this point you've decided to make speaker design a hobby and with all the time going into the effort you're better off starting from scratch.