so from audiworld and a4mods.com i figured out how to splice into the stock BOSE amp and add an extra amplifier to attach to my subs. little bit of trial and error, but overall was pretty simple and self explanitory. great upgrade for anyone who wants to keep the stock BOSE sound but add a little extra thump to it.
just gotta clean it up a bit and hide some more wires, and ill post pics.

now all i need is to replace the rear deck speaker with another BOSE one.....

 

I have a 01 S4 with the stock BOSE system. Where did you find the BOSE amp to splice your new one into?.. I think it will be the same?

 

its in the trunk, drivers side, for of the jack
cant miss it

 

where are the pics?