If I didn't have the sub in back I would most likely pull the front passenger door panel off its usually fairly simple like a screw at the armrest and one at the door pull behind covers then it'll pop off. Then I'd look at the color wires that are going into the door speaker, pull the passenger kick panel off and look for those wires and tap into them.
I say passenger side because the drivers side has tons of wires behind the kick panel. I added remote start and its many wires there.
If you get the Lc2i convertor it turns any signals into low frequencies and also it has a remote turn on feature that turns your amp on and off which is nice. I've had several of these and they work great.
Kia could run the wires to the back for the sub on all models and just leave it hanging put I'm not sure about that.
Last edited by jaxterra; 03-06-2019 at 02:23 PM.