hey hows it goin i just did an install on my 08 si coupe.
here it what you need:
metra harness and wire tap
heres what you do just take your after market head unit harness and wire it directly to the metra harness L+ TO L+ AND SO ON.
then on the small factory plug tap the amp turn on wire from you head unit to pin 15 of the factory side harness. metrra's directions say its sixteen but the harness on the back says 15 so i went with what honda said cause there is no wire in pin 16.
then connect harness to harness and enjoy the better sound!
http://documents.victorytechnologies...oduct/2250.pdf
i will get pics up tommorow cause i have to redue my d1 bypass....cause it said just hook it up to the + of the parking brake so i thought i could just wire it up to the acc and it would work...but it didnt.
so pics will be up soon....
hopes this saves some one 20 bucks or so on rca's enjoy!