most of the time a dual din unit with a dash kit will not fit right, and if you dont use one it looks really bad. There are little plastic wrap arounds you can get to wrap around the dual din to hide the hole it leaves whilst not trying to fit in a dash kit, the dash kit will often times crack and look worse.

i hate to say it, but i use circuit city for harnesses, you can get 2 piece harness adapters for around $17 total that require 0 soldering. if you get the adapter from metra (best buy) it still usually requires soldering to the new headunit harness.

ps i hate circuit city and best buy