well...i don't compete so maybe there are some folks on here that can help with that. But i would think that a big nasty ported box with a traditional alignment would be better suited for that then a clamshell. In a clamshell, the only real thing you gain is space, not performance. You will get the same freq. response from 2 subs in a clamshell as you would from a single sub in a larger properly designed box. Also you lose about 3dbs of efficiency in a isobaric alignment compared to a single sub in a larger airspace. Also you effectively must double the amplifier power in the clam to get the same output