I have a 2004 w/ Bose & no navi and am getting ready to do a DD install myself. I am confused as to which on of these I need. I have searched through the forums & what I found is some people have used either. Also, Crutchfield says I need this

http://www.crutchfield.com/p_1207075...w&rvm=ShowAllt

which looks like the Metra 70-7550. Please advise on which one I need for my setup.

 

70-7551 for Bose.

 

^ not necessarily - it depends on the preout voltage of the deck.
if you have 4volt or higher preout use the 7551 if it's <4 volts use 7550. Overall, there is 0 chance you will get engine noise from the deck if you use 7550 harness and maybe a 25% chance of getting engine noise with the 7551.
Engine noise refers to changing ONLY the deck in this case.

 

The HU i will be getting is the Pioneer AVH-P4100 which has a preout voltage of 4V. So I will most likely go with the 7551 if that's what you suggest. Thanks for the help guys.

 

70-7550 Non Bose system
70-7551 Bose System

 

Troy I was just reading through your post again, is engine noise something I should be worried about with the 7551? ANy way to fix it if it does happen?