I actually just got back from having it installed. The boxes that we were looking at were all down firing and none of them would fit the EV3 and leave enough room for it to move so we put a dual sub box under my seat with a couple of JL 10W1s. After listening to them for a little while, they sounded great but they just weren't enough for me. so we scavenged through the boxes that my installer had and found one made for a different kind of truck but it fit under my seat. We had to take the plastic off the bottom of my seat for both boxes. That box with a .75 inch spacer fit my Sundown EV3 10. It sounds awesome. It feels like it hits harder than both of the JL's. But I ended up ordering a second EV3 and a mid-gate box. That's going to be a few weeks out though because of how rual we are and how far apart the orders are, and because I'm too cheap to pay for $200 shipping.
Lol. Sorry for how sloppily this is written blame it on talk to text.