Greetings everyone!
I am planning to install an amp & sub into my 2001 GTP with stock headunit. My car does not have a Bose system but it does have On-Star.

I was wondering what wire harness I will need to hook up my Alpine amp?
I have one harness bookmarked, but I wonder if it is necessary or if there's something better/cheaper out there.

Looked through six pages of search results, didn't see anything specifically answering my question.

Appreciate input!