pretty much anything you put in will require cutting of some plastic and removal of a small metal brace behind the dash (not a big deal tho).
alot of people seem to like the pioneer avic -d3, the price is right, but i don't care for pioneers gps (personal thing) and giving up the only disc slot for maps would piss me off, I'm looking at the kenwood 7100 and 7120, If i can get some extra cash together i would opt for an eclipse, killer quality and i like the software (same as in toyota and lexus)
bottom line go to a store and try them out, see what you like!
i got the avic Z2 from pioneer the thing absolutly kicks ass. built in hard drive so you can store all your songs and cds and also dont have to have a map disc in the player for the gps to work. the thing is outstanding. but they a bit pricy if your lo0oking for something a little cheap go wth thepioneer avic d-3. its pretty much the same thing but doesnt have the hardrive to store music nd is much cheaper. you can proboly find one on amazon.com for like 700-800$ if not cheaper.
But also im not to up to date on pioneers newest stuff but i do know they just came out with a whole buinch of new seris. F series or something.
But personally i think pioneer is the best head unit you can get. check out AVIC411.com for some more info.
thats a forum of all people who have the pioneer headunits, you will find everytyhing and anything you need to know on there.