Look like older RF subs. No reason they shouldn't sound decent. I've seen plenty of full plexi enclosures. They are usually a gimmick for show cars but they sound fine if they have the right volume of air for the sub being used. Looking at his box, it looks like the tuning might be a bit on the high side.
//content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif This is just me but it looks like a waste of time and money in the back of that car. If he's going to put an "actual" install in there thats one thing but he just shoved it in the trunk and it sort of looks like a fish out of water there. I guess what I'm trying to say is looks like it belongs in a show car.
That just dosen't do justice at all. I could see a large plexiglass box like that in the back of a show SUV or something, with the wires hidden better, but not there. I agree with the tuning as well, ports don' t look long enough.