[JayG]

You can buy the kit on eBay or from suncoast. The kit is easy t install and includes all the hardware and wiring. I put me in. A year or so ago and it makes a big difference. I had the same as you, basic radio a dust dash speakers. I also upgraded my dash speakers.

Don't have any door speakers, so I can't comment on what they add. The factory door speakers are small subs, not full range. From. What I know, it is a PITA to add door speakers as you need to add connections to the door multi pin connector.

I would add the rear speakers and upgrade the dash speakers and see how that works for you before doing any other additions to the stereo