Many (most?) folks just use the speaker out wires directly to the OEM amp when installing a new HU. Worked for me just fine.

IMHO, the OEM stereo is...marginal. Many will argue, but I think it was...disappointing. I installed a Pioneer w/Bluetooth and Infinity (REAL Infinity) 2-way speakers in the doors with the "Most Bang" capacitors and never looked back. Great improvement all around.

There's a ton of threads for swapping it out. "Search" is our friend. I'm sure you know this.