Had a rattle in the door, so I began the <$500 upgrade with front speakers only. Seeing the low quality of the "B&O" speakers I quickly transitioned to a full speaker replacement. Here are pictures of the stock speakers- I couldn't find pics any before I started upgrade. Paper junk. The new Pioneers weigh 2lbs more (each) than the stock fronts. The stock sub magnet is barely bigger than the stock fronts. Amazing what they accomplished with these terrible speakers.
I used the Pioneer 4-ways in the front - the front doors are crossed with no high inputs. The tweeters also stick out so far they touch the door grill. In hindsight I'd probably do a 6x9 2 way or mid only.
I wouldn't bother replacing the rear doors - the stock amp pushes very little back there. Maybe 7W RMS. I used some alpine components and drilled a tweeter into the back door. Can't even the tell a difference due to low wattage.
I used a kicker 1ohm DVC 8" woofer and a JBL 500W amp. The stock sub enclosure is robust due to the molded internal bracing. I had to plug the port due to a resonance at high volume. I think the box is too small to be ported for this sub. I'm using the speaker level inputs from old sub to new amp. Kind of a pain to tune. Even with gain set low and bass set low on the eq the amp shuts down on protect over volume setting 22. But it does shake all the mirrors so good nuff.
Amp placement - I didn't like having wires exposed in the under-seat storage area (because I use that space), so I relocated the jack to the middle underseat area, and made a vertical plate for the amp in the former jack location. You need to ensure you still have space when you tilt the seat base up (the seat-back moves back when you tilt the base). I'm going to mount a bottle jack vertically next to my new amp in the future and ditch the useless stock jack (did you know it's not tall enough to get a front tire off!).
I used Kilmat vs. Dynamat just to check it out. IMO same quality, but 40% cheaper. It really improved dynamic response and road noise. I have now set speed volume compensation to low - I was running it on high. You only need moderate coverage to achieve 90% of the benefit. I did the outer and inner door panels, as well as some large flat areas on the back of the plastic door panels. I got 36 sq. ft., did all 4 doors and the sub enclosure and have about half the box leftover. I will do the roof with the leftovers.
Crutchfield prices were same as Amazon, but Crutchfield includes the Metra adaptor plugs and plates for free (and no mistake!).