Cody Neuman

Hello guys! I've done the research on here and i've found a thread on tapping into the factory amp and i have it bookmarked. They were using and existing rca cable and cutting one end off and using the exposed wires to tap into the wiring. I've decided to purchase https://www.crutchfield.com/p_136XDC...c&awug=9017440 speaker output converter (bare speaker to rca) Is this a good product to use? I would like to verify which speaker wires and amp on wires i will be tapping into. I am installing an aftermarket amp and subs while retainting all factory systems. If you could link me to the correct diagram it would be greatly appreciated.
2008 Chevy HHR 2LT W/Premium Pioneer sound