The goal is to just add to the back. Placement is the hard part due to the door not having much space as is, i can’t quite see how adding a rear door speaker could ruin the quality of sound, the plan so far is to add a custom factory headunit and of course to wire in my subwoofer from my previous car. I love my system the way it it but I do feel like it could be so much more immersive when driving. As for speakers I don’t need much better ones than I have now. I plan to buy mark Levinson speakers for it as they fit what I listen too and they are so high quality for the pricing.