Anyway, I did not see response to my question, so I went ahead installed my Pioneer AVIC-U310BT.
But I installed it little differently than whodat90. I installed the antenna on the dash itself, but under the center speaker plastic cover( I do not have center speaker).
I did some tests before finalizing that location. I installed it temporary on roof, tried it, put plastic cover over it( the center speaker cover) and tried it. There is no difference in signal strength. Then I tried on dash with and without plastic speaker cover. Overall there is very minute difference between installing on roof vs installing on dash under the speaker cover, which is hidden, no need to run long cable etc.
But the problem with installing there is, there is hole in the center for speaker. I could not stick that metal antenna base sticker in proper place, so I made a small metal(steel, no aluminium) bridge over that. This way I do not need to make any holes to bring antenna out.
Since this is metal, no need for that sticker they provided to stick antenna on.
I was able to bundle up all the wire without touching any other wires and just kept the required length.
I got remaining Kit from Crutchfield, the Wiring harness, and Metra Double Din Dash kit. Initially thought of crimping the connections, but I saw several websites recommending soldering for good long term connections. I also saw the advantage of not having all the butt connector hanging behind radio(potential for noises). So, I soldered and taped individual wires, then bundled each set, then bundled all of those with zip ties.
For proper grounding I also used the grounding connector provided by KIA for the factory radio. This way body ground and actual radio circuit ground levelled or matched. Also, I grounding the parking brake connector so that I can use keypad, and enter the destination without pulling the handbrake. I have not seen any issues with this approach yet.
I was able to route USB, MIC, Aux cable independently so that other power cables do not cause any interference. All are tied to body with zip ties so they do not hang and make noise, and also can not be pulled from behind the radio accidentally.
I still have not decided on where to put the MIC. Based on initial testing, for me and my wifes seating position, under the rear mirror seems to be best option. Still have not routed it there, not sure how to mount it there.
USB and AUX cables, I ran under the Glove box with a intent to run those to center console when I get some time.
Overall I would say install went well without a hitch, thanks for all the detailed instructions and photos provided on several threads.
But, that does not mean I like the Unit itself. Audio is fine(still need to get used to operation), but navigation seems lagging behind few seconds behind actual position, so you may miss a turn before it showed( no GPS signal issue). Also, sometime, the directions shown on the screen and voice are not matching!!? My $60 Omnitech(staples) GPS has better routing, quicker response, better layout than this.
Any another issue, contrary to what is mentioned on Crutchfiled about SD card playback, you can not play music from SD card. You can only download POIs, voices, or upload route information.
And for POIs, there is no category for restaurants!!? Do you believe they have cemetery, but not food!? May be people who buy this unit are looking for easiest way for cremation.
And another main issue, Bluetooth. The pairing, dialing everything is fine, but MIC is the worst. I have to talk into the MIC directly very loudly to hear anything on other side. I was able to call my office Audex telephone system which gives several option to record voice and playback, erase, re-record etc. It also identifies if the other person is talking or not. Unless I shout into the MIC, nothing is being recorded. There are no options to adjust the MIC gain anywhere. Listening is fine. I have Prius with in-built Bluetooth and that is 100 times better. Anyways, I went ahead and tried couple other Handsets with the assumption it did not like my phone, but it is the same story.
One main reason I bought this is for bluetooth. It is really disappointing. I would not give up yet.
Another issue, You can not use dialpad once you are talking!!? What the hell they are thinking? Many customer service calls, many voicemail systems need us to enter keys to proceed(like checking my home phone voice mail). They claim it is designed by Parrot.. so much for that.
If I had to do it all over again, I would have picked Kenwood 5120 which is on sale for $499+ Bluetooth kit($100). It is only $100 more, but it defintely worth it.
Anyways, one lesson learned, hopefully it is useful for someone else, and here are some photos of installation.