Go to Crutchfield, they have a "Outfit my car" feature that will tell you what speakers you can fit with no mods. You can usually put any speakers that are close to the same demensions also, but they strictly list the just bolt right up stuff. As for what speakers, I would go with the Alpine you won't be dissapointed. Here is a
GREAT site to buy from if you will install yourself,
http://www.onlinecarstereo.com
I wish I had found them years ago
I bet you could upgrade to the next model of speaker with the money you save over Crutchfield. You should have done the door speakers first, you would have a much better sound stage that way. If you got the cash I would go with a Digital amp. The Alpine pdx line is almost affordable on that site. If you do a little googleing, you will find the PDX line has Bang/Olfesen innards, very good stuff (I have a pdx5 and pdx2.1)
Aside from having much cleaner sound a digital amp is also WAY more efficient and won't draw near the power for the same watts as class a/b amps. This means It wont get much more than warm, you can use smaller wiring, fuses, etc (saving money) you can get way more watts before you have to get serious and put in a cap, extra battry and or alternator, and it won't put near the drag on your existing alternator allowing a longer service life.
Buy a door panel tool, cheap and won't break all of the cheap plastic fastners. Are you running your 300w 6 x 9's off of the deck? Spring for the PDX 5 and it can do the whole system with room to spare, mine was speced at 107w x 4 and 436w x1
Good Luck!
