Well maybe you can help me figure out my boxes, when I ran the skar vvx in just some boxes I threw together to test out of some 1/2" cdx plywood I had laying around, which was meant to be just for a test only and then build better, but they worked great so ended up sticking with them, got the larger zvx and put into the boxes and sounded ok but not near what they are capable of, so I went ahead and made new sealed boxes, like sealed better, I listen to country and rock for hours every week.
using 7 layer 3/4" veneer plywood, threw each panel on my shaper and put a lock miter on all corners, made center support, I could park a semi on the boxes, had everything sanded and painted, connections in the back run to 4 brass bolts on each box, each bokt is siliconed and sealed tight, for each voice coil, 14 awg from each terminal to copper lugs on each bolt then 12awg to lugs on the back, no flimsy box conectors. I have modified the boxes 3 times and can not get them to sound how I want, they still sounded better in the 1/2 plywood boxes.
my end result atm is .6528 cu ft and reccomended. 65 cu ft for sealed box, took the supports out, and still I can not get them to sound how I want, the vvx which is half the size 400 watts rms vs 800 watts rms sounded better, just wanted more, but need to stick with 8's and small space due to needing the luggage room every week. I started with the skar with the vvx 8v3 's and a mb quart 1200 x2 amp, like the skar I kept going with skar all around, but these zvx 's are driving me up the wall.

one of the best I have liked was the 4 audiobahn ultra excursion 12's and 2 power acoustic 2400 amps with glass fronts and dual blue meters on each, in the hatch of a 88 camaro, I had 2 different boxes that big box for shows and a smaller box for normal days with a much smaller setup, made it to take in and out. The audiobahn busted my front windshield, didn't think there was any chips or cracks in my windshield, but didn't think it was big enough to do that, but I could not sit in the seat and turn up the volume.

Mine
Kenwood kmr-d558bt
Skar tx65c components on factory amp
Skar tweeters on dash beside a pillars
Oem tweeters in door on factory amp
Skar skv2-1500.1 amp powering
lithium cell built and mounted by amp
2 Skar zvx 8 subwoofers in 2 seperate .6528 sealed boxes