How do i put an aftermarket stereo into my saab 9-5?

[Bri]

I have a 2000/2001 Saab 9-5 w/ Harmon Kardon. What do i have to do to put an after market Deck, and wire for subwoofers? Every place i have gone has said its more money to do my car because it is a saab. I decided i did it in my 98 Maxima i can do it in this. Any help or recommendations would be greatly appreciated!

Also I have 2 10" Kickers running off an 800w Rockford Fosgate Mono amp. What should i get for a deck?