2 12" L7's ported or 2 15" RE SEx sealed

[hitmeupz]

What's up, hoping you guys can help me out here. I currently have 2 12L7s sealed feeding them 1800rms clean power. It slams pretty good, but I recently purchased 2 15" RE SEx subs. Here's the thing, my car's trunk is pretty small. I was thinking about going ported compact kicker design 3.5CF tuned around 33hz for the pair or 4CF sealed which is the optimal recommended for the pair of RE 15s. Which do you think will slam harder? I could also do either a single 12 or 15 ported in a bigger enclosure, but wouldn't a pair be louder? Thanks in advance.