I know there is a lot of info of replacing the head units on 2003-2005 Most stereo systems. My car is non bose but does have and amp and 6 speakers. Is there a difference between using the metra harness vs bypassing the amp. If so which is better? I understand the metra amp provides 4 channels which matches the Porsche system. Meaning it will use the stock amp to power the 6 speakers with 4 channels and the oem crossover. Is this correct. I am confused on this issue and trying to decide how to move forward.

 

Only way to use the stock amp to power the speakers would be to use the metra harness. In order for that to work you would need to buy an audi harness that transforms the speaker the rca out of the aftermarket to plug into the stock harness that powers the amp. If you wire directly to the speakers that comes from the amp you would either have to have the deck power the speakers or buy a new amp.

 

what are the part numbers for the harness?

I have used a harness on a BMW which passed through the factory amp which i think essentially double amplified the signal, but it worked.

 

Here you go guys... this should help...

http://www.pelicanparts.com/techarti...io_Install.htm