I ran my solo 8s in .33 cubes each. The enclosure was just large enough to fit the driver and nothing more. The actual spacing between the pole vent and the wall was no more than 1/2", probably less, but I remember being worried about it. Never caused a problem. I beat the hell out of them with an A600 mono and they never once screamed. Our whole dilemma is depth, which seems to keep us from regular mounting the subs. My question is, do you think they'll sound good inverted? It seems like a lot of the sub's frame/magnet would block the soundwaves. It doesn't work like that. The omnidirectional waves don't act the same. Does downfiring a driver affect the "sound" of the bass when it's firing at a floor? I know your problem is depth, but do you just no have enough or do you, but you're worried about blocking the pole vent?