i am going to buld 2 tempest sono tubes. the tube will be 6 feet long and 18 inch in diamiter. they will be horisonal in a tabble type of setup so the 2 tubes will be stacked with a 1 inch gap between tubes. now hwere is my queston should i put both drivers on 1 end or should i stager them? now i have enough left over 3/4 mdfb ti buld the ends with 2 layers of it nd olny i layer in the tube and one on the outside with a gruve fot the tube to set in. is this enough or should i get more bord. also should i go pr or port? and if i go pr should i get a 18 pr and go with a 20 inch tube?