How to add aftermarket subs and amp to an 08' Chevy Cobalt w/ stock pioneer system?

[CliMaxXx]

I've tried simply connecting the LOC to the wiring in the back of the stock h/u and also tried going off the 6x9's in the trunk, both of which failed. So I chatted it up with a friend who has a more considerable amount of knowledge and he said more than likely imma have to "bypass" the factory amp. But i want to keep my factory sub and everything. So I would like to know where this is located, and the steps i would have to take to connect a line output converter (LOC) up to my current factory system.

^_^ help mehz plzz

[MrCobaltss09]

wire amp and sub to stock radio

this will help this convo has the how to in it just scroll down a little