What size cable do I run from an amp rated at 130w bridged rms feeding a sub rated at 300w rms ?. Also the front OEM dash speakers are mounted sort of suspended in mid air i.e. there not mounted into a surface, just screwed to two tabs, would there be any benefit in making some sort of board to isolate the front of the speaker from the back as I'm upgrading these speakers too.

Cheers,
Anthony.