monsoon crap is monsoon crap, it only works on monsoon crap lol so you could gut and sell off the amp and bass speakers back there.

new hu and new amp all new speakers and wires to them cause the monsoon stuff is super thin and dont work well for normal speakers.

easiest route here clearly is buying the right new speakers.

i almost forgot, if your speakers are rotted out around the cone to frame, they sell a kit to fix that. seen a few guys go that route as well.