As a professional car audio installer I strongly recommend trying to rerun your power wire down the driver side of your car. You always want to run it down the same side as the batter. You'd also want to go through the grommet not through the outside of it pressing against the metal. there is a plastic cover where the clutch plate would go, i recommend going there to run the wire into the car. Your are much less prone to problems this way. going across the engine you increase the heat against the wire as well as have it rub against the metal between the firewall and grommet.
MECP Advanced Installer