I've had a trunk mount battery (Direct Connection kit) in my Challenger T/A for about 30 yrs, no issues, cable mounted inside under the carpet, tucked inside drivers sill, over the rear wheel well, clipped along the underside of package tray/rear qtr,...battery on the PASSENGER side...use a grommet where it passes thru the firewall to the starter, on an auto car, you could use the clutch rod hole, I prefered to exit just under the firewall pinchweld flange...but again use a grommet and secure the cable WELL, as it will be the biggest smoldering wick if you hack it in the car