Ok, So I've done some searching but I remember that prior to the website re-do, there were plenty of posts on how users replaced their stock sub in an 03. Looking now, I can't find much (can't do a search on a 3-letter word) and the archives seem to go only 250 posts back. Can someone help me on a best practices? I already have the amp/box so I don't need advice on that equipment. I know there are interfaces between the stock HU and an amp and also, people have attached to the existing wiring for the factory sub (not sure if it's pre/post factory amp though). Any help would be appreciated. Thanks,

 

Take out the rear seat back, and you'll see the sub amp mounted back there on the passenger side. The signal wire is in a brown sleeve going into the amp. There's an orange and blue wire in the brown sleeve. Hook up the blue wire the the center pin of the rca, and the orange to the sleeve of the rca, and there you have a preamp signal to plug into your amp. I just hooked up 2 rca's, to plug into the L and R of my amp. Others hook up 1 rca and use a y splitter

 

i tapped these wires too. mounted the amp on the side of the trunk like this:



grounded the amp in the spot where the little gray hook is mounted.

ran the remote wire here to the spade labeled 's' ( under dash on driver's side ):