I have a Nissan 350Z 2003 with the factory Bose System. An after market cd/radio was added: the Pioneer FH-P8000BT Double-DIN CD Receiver with Built-In Bluetooth®. But I wanted en extra tight clear bass punch/kick to the system, so I had a shop add 2 Kenwood KFC-XW12 - 12" 4 Ohm Subwoofers in a...