I'm not familiar enough with the factory head unit to know if it has RCA outs on it...doubtful. You could prolly go the OG way, and use the rear speaker outputs as a high level input, or buy a speaker level to RCA converter. The premium Alpin audio has a dedicated amp mounted on the rear deck in the trunk. You maybe able to decipher the wiring schematic on the input, those should be low level outputs, and you would be able to splice your own RCA's into those wires. Wish I could help more, but I haven't taken a close look at the audio hookups yet.