unless your running multiple lengths of 1/0 or larger, no need to go under the vehicle. if you want to go through firewall on passenger side, you need to drill and install your own grommet or snap bushing as suited for your wire size. drill from inside to keep as close to your floor as possible, then run your wire under the door sills and behind the c-pilar trim (depending on where your amps are at). its more work, but its a cleaner install and you wont have to worry about your wire under the vehicle