Hello, I want to tell you my feeling after changing my sub enclosure. Some people are afraid of going sealed with the Xcons, and want advices. I had a 3.5 ft3 sub box, tuned to 32 Hz. Design was made by Fisher Customs (need the new ones JBL Camry, please). My car is a hatchback car, and I had the sub and port facing up. I loved it, but I could not put a bottle of water (or whatever) in the trunk, and the amps were not breathing right : no room at all. I made a friend (he has an Xcon 15" too) build a sealed box for me : dim are (70 x 40 x 40 cm), so 27.6" x 15.7" x 15.7 ". I think they fit in the ones provided by ssa. I have a lot more room in the trunk and I like that ! I can put some groceries in it, or some tools I had under the seats !!! I have the sub facing the rear of the car , because i put back the hatch cover. Honestly, I was afraid of loosing output, as I'm still a basshead ! I can't say I lost something. The bass still hits so hard . I did not have time to make serious listening sessions, but so far so good. I'm sure it goes lower now, I can feel it easily. I set the ssf to the low, but I think I will try to run it a little higher, like around 20 Hz. What do you think about it ? I will give you more info later, as I get used to it. I will post some pics of the box and the trunk later. Not too much sun today !