if you're talking about the sedan (I dunno about the coupe), the front speakers are shallow 6-1/2's and the rear deck speakers are 6x9's. I bought shallow-mount infinity reference 6002si's that sound great. I'm not sure if shallow 6.5's are completely necessary since I had a little room to spare with those, but I wouldn't get the deepest 6.5's either.
If you want excellent, inexpensive 6x9's get the infinity reference 9603i. Crutchfield's got both on sale now.
Both pairs sounded good running off a sony HU but if you amp them they'll sound incredible. And all for a combined $160. Happy hunting!