I hate to dig up old posts, but this one really saved me a lot of trouble. To add to the info above I purchased the Rosta kit for my 2015 LS w/CVT. The dealer wouldn't install it so I did it myself. Took about an hour tops including soldering in the three connections that you'll need to splice under the dash. The rest is a total plug-n-play operation.
The biggest problem I had was trying to find a good spot to place the controller/computer from the kit. I found that if you pop off the fuse panel and pop out the side panel adjacent to the door that you'll find a nice pocket there to mount