9G Infinity aftermarket headunit with factory amp?

I've spent a couple days digging through 2-3 different Galant related forums trying to nail down all the information I need. Quite a search and I'm still confused on a few points.

I'm just looking to swap out my factory headunit for something nicer. Mounting is all done and I had no issues powering it up using a harness kit from my old Lancer.

Is it possible to use the factory amp without a ton of speaker re-wiring. I know the pink wire is the amp remote, but are the connections to the factory headunit data lines, or can I splice my new HU wires into the amp wires at the headunit?

9G (2005) Galant ES with Infinity 6-disc.

Thanks everyone!