Is it true if I were to run 0 gauge or 4 gauge wire in my 08 350z some of the pannels will stick out a little because of the thickness of the wire.

 

For power run it under the carpet down the passenger side, its real easy. I ran 12 gauge to my door speakers from my amp behind the passenger seat with 0 trouble, no reason to use a lower gauge for that.

 

i see well i call a few places to ask on pricing to have my wire run from battery to cd player to the back. they told me some of the side panel's they would have to remove will stick out some due to the size of wire so i had to ask to make sure.

 

I ran 4 ga. from the battery to my 2 amps in the glove box area, and I didn't have any issues. Use this DIY:

http://liljerk.morpheus.net/350Z/firewall/

 

If this was a shop that told you this, it was just them covering their own butt for the shoddy work that they would do if you brought your car there. Seems like a giant red flag to me. A shop that would do the job right might charge a little more than the others, but they can surely run 0ga wire without leaving panels sticking out. If you're not going to DIY, do yourself a favor and find one of those shops.