5BW rear deck speaker upgrades?

[conipc]

Don't want to get into an add-on sub, so what might improve the rear 6x9s?

 

[beamon]

Agree…definitely needs more bass on lower end

 

[conipc]

Looked at the current OE speakers, and they are pretty lame. Seems like they'd have to come out from inside the car, and there's probably not a lot of room to work...any thoughts on that from anyone??