$190 for a AVIC Z-2 install on a 2003 G-35??? And you question whether or not you should go back to the installer and have him correct the installation.
Of course you should! You were charged for a proper installation you didn't get it. If they are doing the install for that amount it should be correct and complete. IF you paid $500 for the install you would go back why do you have to question it on a $190 install.
Usually people get what they pay for but if you get charged for something you should get all of what you were charged for and that includes a proper installation.
Cannon