I was wondering if someone could give me a hand in regards to either making a new ported box or converting and existing sealed enclosure to a vented enclosure. I have changed between vehicles that had 2x12inch kicker impulse subz installed in them. This box was made as sealed enclosure and of the maximum enclosure size is 85 litres (im from OZ LAND) or 3 cubic feet. I had put my 2 year old box into another car that basically has hardly any room in the boot and its a hatch (1989 z31 300zx, you guys would know these cars) the main problem is since the box don't have much room behind it while being sealed, it does not reproject the bass into the car thus making it flat, I was considering to either make a new box which would be vented or just put port holes in my existing box. The main two questions is if I choose to put port holes what size would you recommend if not how big does a vented box have to be at a maximum enclosure so I can design it to fit my boot.