Well, I'm not sure how the BLs compare with the BTLs, but being that I'm giving them similar power they'll probably be pretty close. I have 2 18" btls fully loaded in my 99 yukon. Each one has about 7.5 cubes net tuned to 35hz with about 115sqin of port each. I have each one run off of a hifonics bxi2006d. I'll be putting about 4-5k watts on each one within the next two months, just have to figure out what amp to get. I've had a lot of setups, but I definitely like this the best so far. Last two were a single kicker L715 on 1300watts(5cubes 32hz), and before that a single alpine type-x12 on 1300 watts(1.1cube 32hz). The alpine did have a bit more distinction with kickdrums, but the kicker was MUCH louder. Then the single btl 18 was MUCH louder. Now that i've had both 18s a few months I've noticed the change in how they play, and I will say that they aren't amazing on kicks or anything, but they're almost comarable to the alpine type-x 12. They sound better than most 12s and 15s I hear. On top of that they are AMAZINGLY loud. Today I met a guy who told me he used to do comps with a honda accord with 6 12s and metered some rediculous number. He asked to hear my subs since he saw them through the window, so I let him sit in there. I played Jeezy, first track on the new album, and as soon as that first note dropped he cringed and put his fingers in his ears. A few minutes later he complained that his ears were still ringing, and that it must've been a while since he cranked his system up. They're the loudest two subs I've ever heard, and sound better than many of my previous 12" setups. The biggest thing I've noticed is the low lows are very strong. I'm sure you'll love them, and if you ghetto-blast near people you're bound to get attention. I guess my point is they don't have quite the SQ you might find in a highend SQ driver, but they still sound extremely good, and have enough output to make up for any SQ downfall they might have. Plus the fact that most people say 'holy-crap thats a big speaker'. I'll upload a few pics of the setup tomarrow when there's more light.