I just installed a pioneer avic-x910bt in my 05 Sedan. I used the JDM DD kit (matches perfect!) I also used the PAC wire harness since I have budget constraints and will have to keep the crappy bose speakers for a while. I wired everything up and it sounds ok but I have to turn the volume up to 30 for any decent sound and by that point the subs are thumping to no end. I was wondering if I needed to connect the speaker high inputs aswell. I did the basic green to green, white to white etc. On the PAC wire diagram there was an extra set of positive speaker wires. i.e. Green/Red was positive high and Green is positive low (for the left front speaker). White/Red positive high and White positive low (right front speaker) I wondering if both the positive high and low have to be connected to the avic wire harness. Any help would be great.

 

Did you use the PAC ROEM-NIS2, or a different harness?

If it's the PAC ROEM-NIS2, this post may help you out:
https://g35driver.com/forums/5032457-post48.html

And if not, ask zeyn83 for help, since he's got experience using it.