i am going to buy two pioneer 306c's and was gonna make a ported enclosure for them. The dimensions i picked out were going to be 17inch length x 15inch height x 18inches depth. Thats the external measurements if they were individual boxes soo with a combined box that would be 33.25x15x18 with a chamber divider would equal roughly 1.8cubic feet per chamber with a 3 inch diameter pvc tube rougly 7 inches long in each chamber to tune to 33 hz... my question is if the box is too square? or does that sound alright?