There's a thread here where I posted photos and notes on my sound system upgrade:
http://www.kia-forums.com/4g-2011-o...reo-speakers-recommendations-improving-3.html
Unfortunately it looks like the photos aren't showing up anymore.
I did almost exactly what it sounds like you want to do: upgrade the sound quality without losing any amenities or advertising to thieves that you've got a nice aftermarket sound system.
Here's the Cliff's Notes:
- Dynamat on the floors, doors, and trunk, plus Dynapad on the floor to deaden outside noise.
- I kept my factory head unit (the baseline model in the LX), which doesn't have pre-amp capability. This means I needed a line output converter, which is mounted under the front passenger seat. It is an Audio Control LC6. Factory wires run from the HU to the LC6, while Stinger RCA cables connect the LC6 to the amp
- The amp is an Alpine PDX-5 mounted to the backside of a back seat. 4 channels @ 75w, 1 subwoofer channel @ 300w
- My subwoofer is a 12" JL Audio W3 in a prefab sealed enclosure. Optimas have a place to install a subwoofer on the rear deck (8" or 10", I believe), and if you have the Infinity system you may already have something there. On my model, there an indentation in the sheet metal, but cutting would be required, so I went with the 12" in a separate enclosure.
- The subwoofer volume knob is mounted inside the center console bin.
- The front speakers are Infinity Kappa components, which come with crossovers. Tweeters in the dash, woofers in the doors, using more or less the factory mounts (the tweeters required an additional bracket to fit, but once the covers were back on, you couldn't tell.) The crossovers are in the dash behind the head unit.
- The speakers in the rear doors are Infinity Kappa 2-ways, again using the factory mounts.
This was a massive upgrade to the factory sound system, but it's totally a wolf in sheep's clothing. You'd never know it was aftermarket unless you saw the sub while the trunk was open (or you heard it). Plus, I got to keep all the factory amenities.