im taking it you already bought the speakers?
if not, my advice is to go with what everyone else is saying... just buy a really high end set of comps for the doors... 8" subs are going to do nothing but make your door panels and outer door skins rattle like hell and sound like complete ***... if you dont want the "gangster rattle" from your car, dont put 8" subs in the doors cause that's what you're gonna get