Reverse wiring harness for amp
 

I am looking for this harness from a 2013 brz:
https://i.imgur.com/iFgWvtX.jpg

Any idea what part number for subaru or metra/scosche that would be?

[ame="http://www.amazon.com/gp/product/B00029X1KA/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX 0DER"]This[/ame] looks like the harness to me, but I want to be sure that it fits.

What I am doing is connecting a Metra 70-1761 to a factory harness, making basically an extension cable that I can then splice to an amp for a subwoofer. This is just to avoid having to splice the factory cables.

I think that you're looking for metra 71-1761
Edit: it may need to be repined to do exactly what you want b/c the back amp pinning is a little different than usual config