The 2013 kia optima comes in three different audio configurations. one configuration has a navigation system, one has an infinity audio system, and one has neither. regardless, your speaker sizes are consistent throughout. in the center dash, you'll find a 2 ohm4 inch center dash speaker. in the corners of the dash, you have 3-1/2 inch speakers. the front doors are equipped with 6-3/4 inch speakers, while the rear deck has an 8 inch speaker. finally, the rear doors are fitted with 6-3/4 inch speakers. these are relatively common speaker sizes, so they'll be easy to upgrade to aftermarket equipment if you wish. audiophiles will love the upgradeability of the optima's head unit, as many compatible options can be found through major manufacturers like kenwood, alpine, and sony.
The 2013 kia optima is equipped with 3-1/2" corner dash speakers, 6-3/4" speakers in the front and rear doors, and an 8" speaker in the center of the rear deck.