Installing my mobile amateur radio rig in my 2004 Chevy Impala, and I need to run a cable directly from the battery terminals to inside of the car (rig mounting on hump by front seat). Is there a convenient place to pass thru the firewall? - it's (2) 10gage wires. Looking at a grommet on the passenger side floorboard where a bundle of cables pas thru - is it a good place or is there some place 'better'?