I have a 2006 gmc sierra, extended cab, with the factory bose system. I don't have the factory sub in my truck. I wanted to install my kenwood head unit, but I soon learned I needed 150 dollars worth of adapters. So I installed my amp and sub using a line out converter (loc). I spliced in the loc at the wiring harness, right underneath the cup holder. Is where I spliced in at after the factory amp? Should I have spliced in at the factory amp wiring harness, which is at the very back of the center console? The reason I ask is because the sub barely sounds like its on. Also I was wondering if the factory sub is visible if you pull out the cup holder? The reason I ask is because either I don't have the factory sub or it doesn't work, if its not visible. Thanks in advance.