Useful thread here with specs for original driver and possible replacements: https://www.google.com/amp/s/www.talkbass.com/threads/ibanez-promethean-p5110-speaker-upgrade.874880/%3famp=1335303606
Also check out input from our own @StraightSix , the OP of the Talkbass thread:
The promethean uses a slot port, so I imagine altering it would be virtually impossible, especially in a cabinet this small. So if you decide to replace the driver you're stuck with whatever works with what you've already got, but from briefly reading the 2 threads I've linked it looks like improving on previous performance will be no problem if you're willing to spend a little bit.
This thread is making the aged Celestion in my Ashdown 1x10 combo feel extremely nervous...