You won't get "direct plug and play". The stock speakers have this funky plastic mounting bracket and the stock holes are not in "normal" positions. You could drill new holes in you door.... shudder....
So a couple of things that you should consider. You'll need a mounting bracket. You could buy one of those crappy black adjustable plastic ones, or get one that's custom made for the car like
http://www.subaruaudio.net/subaru-sp...nd-scion-fr-s/
Or you could make your own.
The second thing to consider and really the reason you are doing this, is you want your new speakers to push up against the door trim - this seals the speaker and pushes ALL the sound out into your car where you want it. The factory speakers actually do this. If you do that your mid bass will bang.
Oh, and while you have the door trim off, I'd put in some sound deadening