I currently have two Obsidian Audio OA12 V2's running off of 2 Audiopipe APSM1500's strapped @ 1 ohm. I used to own a Fi BTL 12" UFO motor sub before this system but on less power. The guy that currently has my old BTL is wanting to trade straight up for my two Obsidians. I think my Obsidian setups is a bit louder than the BTL was, but I really liked the way the BTL sounded, and it's able to handle the power I'm currently running better than the OA's. I'm considering the trade, but I'm looking for other opinions on whether or not this would be a good trade or not.

I liked my ufo subs  

Maybe trade and add a second btl? Is that an option?

No, that is not an option. I am running in a trunk of a Grand Am. The box I currently have for the OA's is even under recommended volume, but it's the biggest I could fit and still be able to put it in and remove it without any issues. The box I have for the BTL is also the biggest I can fit, but is actually built to specs of the sub.

I would probably go with what sounds best to you. It may be not as loud but it is in the correct size box. Are you sure you couldn't fit 2 12s or a single 15? The first real build I saw when I first started out was a single 15 bl in a grand am. Then he switched to 2 bl 12s. Although he could of not had the box the right size for them.

I was thinking about reconing to a 15, but I'm not sure about being able to fit it into the trunk. I have to slide the BTL in through the back seats and it barely fits that way. I only have about a 16" clearance to work with unless I built the box inside the trunk, which I'm trying to avoid.

Maybe I can get a hold of him a see what his dimensions were. He had is front firing though.