yeah that'd work fine. i hear the more square the port, the better. prevents the 'pinching' of the air through the port. and same chamber doesnt hurt. that's how lots of people here including myself have their setups. only thing is, say you have 12 cubes of air, 3 for each sub, and one stops working, that's gonna divide the total airspace to the working subs, giving them 4 cubes of air. but i like common chambers