Trying to put 2 Jl audio subwoofers in my 2014 Scion FR-S
 

I went to put my subwoofers in the other day and bought and amp install kit. When I was wiring it to the stock pioneer headunit I realized that the headunit for the 2014 doesn't have the rca input cable (red and white). How and where can I buy a converter and how do I wire i. if anyone could help me out and tell me what I need and how to wire it that would be cool!