i have a 2001 a4 b5 1.8t that has the Bose speakers system. i want to replace the system but i don't know all the speaker sizes and i would like to buy the speakers before i start tearing my car apart. i also have been hearing that there is an amp somewhere in the trunk and i cant seem to find it. can anyone help? also i don't know much about different speaker brands, what would you recommend?

 

Bose amp is on top of the left rear wheel housing.