I used Diamond Audio for my speakers and amp. 2, 4 inch round in dash, and 2 6x9 in rear. Diamond uses a different material for their drivers which are more weather resistant. If your trunk is like mine it's bare metal with some holes in it. I mounted my Amp underneath the driver seat which powers my 4 speakers. My BT media player is mounted under passenger seat. As a previous poster mentioned I ran a Infrared censor from the deck to the dash which allows a remote signal to hit it. Since I don't have passengers I used a Amp/Sub low profile combo and set it behind the driver seat. Can be easily disconnected if I need the space or want to move it, otherwise it stays pretty hidden. Outside of an Iphone chargering wire coming out from seat, you don't know it's there.
i'm very pleased with the sound quality, and the small sub rounds out the lows so it's not too overbearing.