This is just my opinion, but if it were me, which it was when I did my install about a month ago. I went with a head unit, component speakers and a 2 channel amp. It allows you to get not only better quality sound but if you get some decent speakers it will give you some bass that the stock system lacked. Buddy has the x305 in his s2k and he doesn't have any fitment problems.

 

I haven't had issues with my iDA-x303 and I believe the only difference between that and the 305 is the display. The door does hit up agains the knob but can still be closed.

If you are just going to upgrade the HU and speakers, then the Alpine might be the way to go since you can also add the KTP 445 (power pack) to help boost your sound. I have the iDA-x303, KTP445 and SPS600C speakers/tweeters (might as well upgrade those...most speaker units come with them anyway). I have no plans to add a sub or amp, so this works great for me.

 

The power pack sounds like a neat option. Thanks for the suggestion.

 

^^No problem. It does add a nice power boost and is quite affordable as well. I love my setup...sounds great, top up or down. All reasonably priced all together.

 

no problem closing the door with the x305 as long as you don't try to close the door with your figer right in the moddle of the top radio door.

never seen any Sony in serious SQ cars, so that should be something you should consider...

Kenwood eXcelon, Pioneer Premier(top end model only), and Alpine are the only ones I'll consider nowadays...