or you can get PAC's newest interface harness, the OS4. its the same as OS3, but updated. swc are plug and play, no need to find factory wires and do your own rewiring, gives u reverse, speed sense, parking brake (like anyone uses it), and everything u need right at the harness
you will have to do an amp bypass if ur adding an aftermarket amp. im not completely sure on where the amplifier is located, cant recall atm, but you have to tag all your speaker wires there, not behind the radio or else youll be sending an amplified signal through the bose amplifier