So I have looked most of the day at multiple different places looking for a sub and amp addition. I have a 19' OR double cab with the tech package, so I have the JBL system, which is lackluster at best. I am only going to be adding a sub and amp at this time and keeping the HU as is for now. Everything I looked up was pushing people to change the head unit out and doing a complete gut job of the sound system, but I don't have that amount of cash flow for it right now. I have a JL 12W3v3-4 with a box and a JL audio 5001/d amp. What can I do to make this as easy/streamlined as possible to just add it and not replace the HU. Thanks in advance.