Some of my speakers are blown, so I need to replace them. I was planning just to buy new factory speakers (you can buy them individually, not just pairs). Are they difficult to replace, or can I do them myself pretty easily? I can get them installed for $25/ea if I don't feel like messing with it.

Also, this is probably a dumb question, but is there any more sophisticated way to tell which of my speakers need to be replaced besides moving the Balance/Fade around the car, and putting my ear to the speaker?

Thanks!