Amo and Subwoofer Instalation
 

Hi everyone I have a 2007 bmw 525i E60 and I want to increase the power of the sound system cause when I play the music from my phone trough the auxiliary have of the power is lost and is depressing.
I have never installed a sound or alarm system and I need to know if there is a DIY with pics of the wiring connections and all the parts needed to do so.
I read of somebody who adapted a 7" subwoofer in the rear seat arm rest but there was no pics, I liked that ootion since they say a subwoofer in the trunk wont make a lot of diference since Bmws are well insulated, any help will be greatly appreciated thanks.