I have a 2002 Honda Civic Ex and was wanting to know if I got the Left/Right quarter panels, head lamps, hood, and bumper, (all from 2004 Ex) would it all go on with out modding anything?

I like the 2004 look a lot better personally.

 

I believe you are talking about the fenders, not the quarter panels. i used to get those mixed up too. but yes. they should all go one without modification. check out the FAQ's

https://honda-tech.com/forums/honda-civic-2001-2005-78/faqs-guidelines-read-before-posting-2101211/