How do you install door speakers in a 2009 Subaru Forester?

Answer 1

Cant help you with the rear speakers, audio experts would suggest leaving the rears alone and spending twice as much on only the front speakers... You'll have to Google "rear fill" and other topics to understand why, but to get the best quality and imaging, it is best to focus on the front speakers while leaving the rears to just barely fill in sound behind you (so it doesnt feel completely empty). The factory rear speakers are more than capable of handling this task.

Here is a written guide complete with tools needed, interior plastic removal steps, equipment suggestions, and pictures to help you see exactly what you need to do.
It also covers drilling holes for speakers that don't fit, and mounting tweeters in a custom location.

Link: (paste into your address bar)
http://alilknowhow.com/?p=3