www.crutchfield.com They are your friends. The heaven of audio.. Call their hotline or chat with them online for any questions. There customer service is amazing, best service I ever dealed with. I can't wait until they update their products to the BRZ/FRS because I still can't find matching audio products that will be vehicle specific.
Brands I like are JL Audio and Rockford Fosgate I feel their products are high quality and look really nice compared to others.