97 A4 audio question
 

i'm going through my car cleaning it up and doing general maintenance before i have a buyer. one thing i want to do is have the stereo i just bought installed in the car but notice that the one that currently in there is spliced in..... it's a sony deck. there are 3 harness connectors two big ones and a little yellow one.

i think i can solder the wires back to factory original... but think they did what they did to bypass the bose thing or the amp.

first question : how do i know if my car actually had a bose system ? and second question... where is the amp located ? i looked in the trunk but only see the rear deck speakers.

any help would be greatly appreciated.