I'm looking to replace the stock radio with either the Pioneer FH-P4100 or the Kenwood DPX-MP4030 . Eventually I'll be replacing the door/rear speakers with something that sounds better than the stock system. Is it as simple as the other radio install I did in the VW Jetta I have where pull it out of the dash, wire the harness to the receiver, connect it back to the car and in the dash it goes? I'm curious because these show ~4X45W output but I believe the base stereo has 6 speakers if you count the little tweaters in the pillar. Anything I'm missing or is as simple as outlined above?

Thanks in advance for the help and sorry if this has been covered before!