These are the model speakers and head unit I used.
Kicker 07DS6502 DS-Series 6.5-Inch Component System with 20mm Tweeter
Kicker 07DS6930 DS-Series 6-Inch x 9-Inch 152mm X 229mm 3-Way Speaker
The crossovers come with the speakers. When you're using component speakers, a crossover is needed to filter the lower end signal out as the tweeters are just for higher audio spectrum signals. Subs are for very low spectrum signals and generally there's a separate crossover to pass only the low end signal to the sub. High-pass filter for tweets. Low-pass filter for subs. Everything else can go to your front and rear speakers.
If you're going to replace anything, replace the head unit. It will make the stock speakers sound halfway decent. The stock speakers aren't rated very highly as far as power and that's why I swapped them out for the Kickers. I like to crank my music up, roll the windows down, and jam out as I'm cruising.
Originally Posted by bigwayne3000
What speakers did you use? Coudl you point me in the direction. They are Kickers I see but just curious which ones you used. Also, do you need a crossover for each door ie. each front speaker? And Ive never done this to a car before except replace stock speakers out of my Explorer but what does a crossover do? Im looking to add subs to my car via SubThump so I may also just do a complete system redo minus the headunit.