my brother has an L7 12" in his a 1.5 cubic ft3 box. on about 340 watts (jl jx 500/1).
Its ok. nothing to jizz over
He got the sub/amp for free when he bought his car. The receipt in the glove box said $250 for the sub I believe? Which for that money you could get a WAY better sub. I got my Zv3 sundowns for $325 shipped each.
As for sq. I always think it really depends on the enclosure. But I do hear that square subs sound like crap when loud. (i haven't heard his loud since he doesn't have enough power)