I could be wrong, but I believe the battery only needs to be in a sealed box if you're not running a rear firewall that meets the minimum thickness specs.
That actually brings up another question I need to do some research on. Is there a need to use a sealed battery box vented to outside the car if using a firewall? I vaguely remember reading that there's a potential for corrosion issues in the trunk area if you leave the battery open. Is there any truth to that statement??
