Well,I just ordered a Q15 dual 1 ohm sub for my car. I had a 12w6v2 in a jl spec sealed box but after hearing the Q10 in a sealed boxed that I bought for my wife's car (hers goes lower and sounds better than my 12" ,just not as loud)I decided to go Fi also. I have a 06 Jetta and I wanted to run a sealed enclosure.I have lots of trunk space. I know that the spec sheet says 2-2.6 ft3 but is there anyone running larger and how does it sound. I want to focus on sq and very deep lows.