Right now I've got 2 12" subs in the back and it eats up a TON of space. I'm looking at making two custom boxes that fit on the sides of the x.

Has anyone made boxes? And any recommendations. I'm trying to keep the cost to absolute minimum.

Thats funny, i'm actually doing the same thing. I just pick up and Single box today for 40 bucks! My 2 10'' take to much room. As for the second gens i'm not sure what they make.

I've made sub boxes, used to sell them too. It's not very difficult, as long as you take accurate measurements and draw up your plan in advance.

I always use 3/4" MDF, 1 1/2" screws, and vinyl caulk, for the construction, and predrill the holes so as not to split the MDF.

For carpet you can either use felt upholstery, or automotive carpet. More expensive, but nicer looking, vinyl is also a nice option. 3M spray adhesive in the black can works great - spray a layer on the box and a layer on the back of the carpet, and then apply the carpet when the glue gets tacky. Don't use car headliner adhesive, it holds for a while but eventually the carpet will come loose.

To save some money, you may be able re-use the materials from your current boxes. Particularly the fronts, so you won't have to re-cut the holes for the subs.

The most important thing to consider is the volume of the airspace inside the box. Make sure you stay as close as possible to the recommended cubic ft. set by the manufacturer, otherwise the sound quality can suffer, and you can even damage the subs.

edit: wow, sorry - didn't mean for that to be so long!

I haven't yet installed one in the X but it's on the to-do list. I've got a couple 10's in my ranger and I built the boxes for them, almost the same way as anthony explained it, but I used 1/2" plywood as I had a spare sheet laying around.

Def go with the 3M adhesive, it withstands moisture a heck of a lot better than the headliner adhesive (good for trunks that leak a little)

I?ve got an Infinity Basslink apm?ed 10? sub in the back of my junk and it?s is plenty for an old guy like me (rear view mirror shakes when it?s turned up).

You can find them for between $160 and $250. It had provided enough bass and was cheap enough to discourage me from building something. Vertical mounting dimensions (with mounting feet): 15"W x 15"H x 10-1/4"D; horizontal mounting dimensions (with mounting feet): 15"W x 9-3/4"H x 15-1/8"D takes up a fraction of the space taken up by a box. Maybe something to think about.

JL makes a box for us as well, but it's a waste of money if you ask me. If I remember correctly its in the $300 plus range and I don't think it's amplified.

I have a RF box with 12's in the back, definitely takes up a lot of room, I'd like something that doesn't take up much space but still sounds good. I've beenthinking about upgrading my system. Get some speakers for the rear doors, an amp and a subwoofer instead of the box.
This leaves plenty of room in the back!

There was someone a few years ago on XF or XOC that built some very nice built-in sub boxes out of fiberglass. That would be slick.

Jeff, I think there's someone over on thenewx that made some custom enclosures to fit in the rear cubby spaces.