2.5-3.25 net cu. @ 34-36 is a decent all-around box. i don't know the exact numbers on the kicker boxes off-hand, but the tend to be compact, minimum size, and tuned kind of high. they are made for toss-n-go in just about any vehicle. what the subs really like is a lot of box, qand that doesn't always fit into customers plans. don't get me wrong, kicker does put some thought and research into their boxes, but they are not what is optimal. of course, what is best for you depends on your vehicle, what you listen to, and exactly what type of output you want out of it.