You dont have to drill through the firewall, but bot 200w RMS you should use 4 gage power wire, you cacn run it in the joint where the hood, door, windshield meet. There is almost always enough room to run it through there. Otherwise drilling a hold in your firewall is the next best. DO NOT BY ANY MEANS USE A CIGARETTE LIGHTER, OR ANY WIRE LESS THAN 8 GAGE. POTENTIAL FIRE HAZARD!!