I'm new to the site so I hope I'm in the right place. I have a 2007 Chrysler 300 base. I'm wanting to replace all audio components. Starting with the head unit I looked at the wiring harness and looks like there are two one is for, I believe it's the 4 speaker, and 8 speaker. I definitely have the 4 but I want to put in 3.5" when I'm done. My question is, can I go ahead and install the one that is for the 8 speaker and add speakers as I go. Any advice or recommendations would be appreciated, products, things to prepare for ect. I wanna do it up right. I'm good with car audio and I'm an electrician buy trade but every vehicle is different and I'd like to hear from some guys who have done up their 300's audio. Thanks in advanced.