i haven't put one in my acadia but i can help you do it if you need help, i have a lot of customers who pay to add subs to a factory stereo and it is very simple and inexpensive, the best thing to do is to pick out what you will be installing, get an amp wiring kit and an output converter (best buy, walmart) this will allow you to tap into your rear speakers and create rca cables for your Factory HU along with a remote wire to turn your amp on and off.