I have a 2003 Infinity G35. I have recently changed the head unit to the OEM 2004 Infinity G35 stock radio.part number PN2545E however when i hook it up the sound quality is not the same and playing at lower volume. Also it seems like the audio polarity inverted somehow - A assumption due to sound quality i just purchased the head unit off of EBay any suggestions to try??

 

Do you have the bose system in your car? Is the 04 head unit bose?

 

Yeah, sounds like you swapped bose and non-bose radios.

 

Depending on your wallet, the dollar:reward ratio of an entry level aftermarket system would most likely crap all over that of the OEM fix you're trying to accomplish here. My $0.02.