its a LOOOOONG story, but bottom line , DONT. Will post why not from the electronics POV. suffice to say ,if you try to bridge bridged amps , you will end up shorting stuff . its because the HU has built in protection, else it would have blown up long ago...
if you want to drive a sub with the HU, get a DVC sub
If you really want to understand why not ,
HEAD UNIT SPEAKER OUTPUT-BRIDGED?
an explaination of the amp configuration in a car HU.If you can fully understand it , we can talk more :P
I got an amp made locally to drive my sub
http://www.techenclave.com/show-off/...tml#post766915