I have a 2013 XLT supercab with 4.2 inch screen. I'm putting infinity reference 6832's in the doors and a JL Micro-sub with JX-250/1 amp under the back seat. I used the search feature, but found a lot of conflicting info. I know the PAC harness doesn't work, so I'd have to use a LOC. Everyone seems to be tapping behind the head unit, but I'd prefer not to pull the dash off. Is there any reason not to just pull the signal for the sub from the rear door speakers? I've heard people take it from the tweets, but not the rear. Any reason? It seems a lot easier than pulling the dash. I've heard it can affect your sync, but I don't see why it would? Thanks!

 

You can get the signal off the rear speakers

 

Tapping into the rear speakers will work and if you're planning on just keeping the factory head unit then I'd say you could go either way
(FYI - 4 lines on the LOC so you'd have to tap into both side speakers).
But if you plan on replacing your head unit in the future you'll already have your component cables if you put it in the dash.

Pulling the HU appears alot more difficult than it actually is.
Here's the instructions for removal that I stole for the Metra dash kit install when I did mine:
http://www.metraonline.com/files/pro...-5830B_web.pdf
(doesn't say clearly but on step 3 you need to just gently pull the trim to the left of the HU to access the screw)

 

Thanks for the info. I installed some aftermarket speakers today and it did what I was hoping for my highs and mids. I decided just to let a speaker shop by my house install the sub. They only want $80 and they have a good reputation. They said it'll only take a little over an hour and I can wait. It's not worth it to me to mess with it when they're so cheap.