Not sure if this has been covered completely or answered properly but the standard 6 speakers in a crew cab consist of full range 6x9's in the back and full range 6x9's in the front door and full range 3 inch speakers in the dash that get their power from a parallel hook up from the doors. Not a separate crossover. Now that is not to say the door speaker or the dash speaker do not have some type of capacitor or whatever it is called that would degrade the bass in the dash speakers and the highs in the doors. This info is from a stereo technician at a reputable popular online shop. Also recommended a nice upgrade for a nice price including new speakers and an amplifier. With a single amplified sub for simplicity. I am not looking for boom boom I just want a little bass boost I am not doing the sub until after I hear how it sounds with just the new speakers and amp. I will not being doing this until spring but will keep you updated with pics when and really if I decide to spend the money since we really thing it sounds good now. I have a set of kickers 6x9's I might throw in the back now just to see.

 

I upgraded all my speakers and put in an amp. I used alpine 4 ways in the doors and 2 ways polk audio in the dash and headliner. The amp was JL audio. I ended up taking it all out. It was a lot of money with little gain in audio quality if any. The Factory radio dont have the range I was use to in aftermarket Alpine units. I have the RER Alpine Factory system. If your long term plan is to replace every thing then go for it. If you want to keep the factory head unit I dont think your going to get much out of this.