The doors and rears are the same size as the non-monsoons. The dash is where the speakers actually do a change. with the monsoon, there are no tweeters in the a-pillar, and there are a midrange and a tweeter under that grill in the dash.
If you put in an aftermarket stero, i dont really know how you wire it, i know you can still use the monsoon amp, but it has the crossovers built into it instead of built into the speakers, SO if you put a fill range speaker in your door, your not gonna get full-range.
But if you have a full system (like mine) then the only factory wires your gonna be using is the power wires behind the radio and that's it. tee hee.
*** Edit ***
I looked at your link, wow, i thought my wiring was bad when i forst dud my system on the back of my cloth seats. hehe. We did ALOT of the same things. Looks like you did more spl thean sql though, i tried to do sql but with some bling. It's really nice, but with how underpowered my subs are, theyre more like woofers than subs, which is good imho, just not for techno/rap (which a dont listen to that much)
And why are you so worried about hte warranty, if it's pre-owned it doesnt cover much of anything. (unless they changed it) And if your gonna do everything you did to that poor black bug, please dont, there are way too many lights and swithces imho. do you really need your floors to light up blue, red, or green? damn.